diff --git a/integration-tests/tests/pages/search.page.ts b/integration-tests/tests/pages/search.page.ts
index ff10cdc5b2..4ecb9dfb71 100644
--- a/integration-tests/tests/pages/search.page.ts
+++ b/integration-tests/tests/pages/search.page.ts
@@ -31,4 +31,33 @@ export class SearchPage {
     async resetSearchForm() {
         await this.page.getByRole('button', { name: 'reset' }).click();
     }
+
+    async getSequenceRows() {
+        return this.page.locator('[data-testid="sequence-row"]');
+    }
+
+    async clickOnSequence(rowIndex = 0) {
+        const rows = await this.getSequenceRows();
+        await rows.nth(rowIndex).click();
+    }
+
+    async getSequencePreviewModal() {
+        return this.page.locator('[data-testid="sequence-preview-modal"]');
+    }
+
+    async getHalfScreenPreview() {
+        return this.page.locator('[data-testid="half-screen-preview"]');
+    }
+
+    async toggleHalfScreenButton() {
+        return this.page.locator('[data-testid="toggle-half-screen-button"]');
+    }
+
+    async closePreviewButton() {
+        return this.page.locator('[data-testid="close-preview-button"]');
+    }
+
+    async getUrlParams() {
+        return new URL(this.page.url()).searchParams;
+    }
 }
diff --git a/integration-tests/tests/specs/features/sequence-preview-url.spec.ts b/integration-tests/tests/specs/features/sequence-preview-url.spec.ts
new file mode 100644
index 0000000000..52e5d449e0
--- /dev/null
+++ b/integration-tests/tests/specs/features/sequence-preview-url.spec.ts
@@ -0,0 +1,87 @@
+import { expect } from '@playwright/test';
+import { test } from '../../fixtures/auth.fixture';
+import { SearchPage } from '../../pages/search.page';
+
+test.describe('Sequence Preview URL Parameters', () => {
+  let searchPage: SearchPage;
+
+  test.beforeEach(async ({ page }) => {
+    searchPage = new SearchPage(page);
+  });
+
+  test('should store the previewed sequence ID in the URL', async ({ page }) => {
+    await searchPage.ebolaSudan();
+    
+    let urlParams = await searchPage.getUrlParams();
+    expect(urlParams.has('selectedSeq')).toBe(false);
+    
+    await searchPage.clickOnSequence(0);
+    
+    await expect(page.locator('[data-testid="sequence-preview-modal"]')).toBeVisible();
+    
+    urlParams = await searchPage.getUrlParams();
+    expect(urlParams.has('selectedSeq')).toBe(true);
+    expect(urlParams.get('selectedSeq')).not.toBeNull();
+    const selectedSeqId = urlParams.get('selectedSeq');
+    
+    await (await searchPage.closePreviewButton()).click();
+    
+    urlParams = await searchPage.getUrlParams();
+    expect(urlParams.has('selectedSeq')).toBe(false);
+    
+    const currentUrl = new URL(page.url());
+    currentUrl.searchParams.set('selectedSeq', selectedSeqId);
+    await page.goto(currentUrl.toString());
+    
+    await expect(page.locator('[data-testid="sequence-preview-modal"]')).toBeVisible();
+  });
+
+  test('should store half-screen state in the URL', async ({ page }) => {
+    await searchPage.ebolaSudan();
+    
+    await searchPage.clickOnSequence(0);
+    
+    await expect(page.locator('[data-testid="sequence-preview-modal"]')).toBeVisible();
+    
+    await (await searchPage.toggleHalfScreenButton()).click();
+    
+    let urlParams = await searchPage.getUrlParams();
+    expect(urlParams.has('halfScreen')).toBe(true);
+    expect(urlParams.get('halfScreen')).toBe('true');
+    
+    await expect(page.locator('[data-testid="half-screen-preview"]')).toBeVisible();
+    
+    await (await searchPage.toggleHalfScreenButton()).click();
+    
+    urlParams = await searchPage.getUrlParams();
+    expect(urlParams.has('halfScreen')).toBe(false);
+    
+    await expect(page.locator('[data-testid="sequence-preview-modal"]')).toBeVisible();
+  });
+
+  test('should restore state from URL parameters on page load', async ({ page }) => {
+    await searchPage.ebolaSudan();
+    
+    await searchPage.clickOnSequence(0);
+    await expect(page.locator('[data-testid="sequence-preview-modal"]')).toBeVisible();
+    
+    const urlParams = await searchPage.getUrlParams();
+    const selectedSeqId = urlParams.get('selectedSeq');
+    
+    await (await searchPage.toggleHalfScreenButton()).click();
+    
+    await (await searchPage.closePreviewButton()).click();
+    
+    const currentUrl = new URL(page.url());
+    currentUrl.searchParams.set('selectedSeq', selectedSeqId);
+    currentUrl.searchParams.set('halfScreen', 'true');
+    await page.goto(currentUrl.toString());
+    
+    await expect(page.locator('[data-testid="half-screen-preview"]')).toBeVisible();
+    
+    await page.goto('/');
+    await page.goBack();
+    
+    await expect(page.locator('[data-testid="half-screen-preview"]')).toBeVisible();
+  });
+});
\ No newline at end of file
diff --git a/website/src/components/SearchPage/SearchFullUI.tsx b/website/src/components/SearchPage/SearchFullUI.tsx
index 0b1c47911e..df89e8a0ef 100644
--- a/website/src/components/SearchPage/SearchFullUI.tsx
+++ b/website/src/components/SearchPage/SearchFullUI.tsx
@@ -13,6 +13,7 @@ import { SeqPreviewModal } from './SeqPreviewModal';
 import { Table, type TableSequenceData } from './Table';
 import useQueryAsState from './useQueryAsState.js';
 import { getLapisUrl } from '../../config.ts';
+import useUrlParamState from '../../hooks/useUrlParamState';
 import { lapisClientHooks } from '../../services/serviceHooks.ts';
 import { DATA_USE_TERMS_FIELD, pageSize } from '../../settings';
 import type { Group } from '../../types/backend.ts';
@@ -94,10 +95,25 @@ export const InnerSearchFullUI = ({
         return consolidateGroupedFields(metadataSchemaWithExpandedRanges);
     }, [metadataSchema]);
 
-    const [previewedSeqId, setPreviewedSeqId] = useState<string | null>(null);
-    const [previewHalfScreen, setPreviewHalfScreen] = useState(false);
     const [state, setState] = useQueryAsState(initialQueryDict);
 
+    const [previewedSeqId, setPreviewedSeqId] = useUrlParamState<string | null>(
+        'selectedSeq',
+        state,
+        null,
+        setState,
+        'nullable-string',
+        (value) => !value,
+    );
+    const [previewHalfScreen, setPreviewHalfScreen] = useUrlParamState(
+        'halfScreen',
+        state,
+        false,
+        setState,
+        'boolean',
+        (value) => !value,
+    );
+
     const searchVisibilities = useMemo(() => {
         return getFieldVisibilitiesFromQuery(schema, state);
     }, [schema, state]);
@@ -144,6 +160,7 @@ export const InnerSearchFullUI = ({
             page: '1',
         }));
     };
+
     const setOrderDirection = (direction: string) => {
         setState((prev: QueryState) => ({
             ...prev,
@@ -338,13 +355,13 @@ export const InnerSearchFullUI = ({
             <SeqPreviewModal
                 seqId={previewedSeqId ?? ''}
                 accessToken={accessToken}
-                isOpen={previewedSeqId !== null}
+                isOpen={Boolean(previewedSeqId)}
                 onClose={() => setPreviewedSeqId(null)}
                 referenceGenomeSequenceNames={referenceGenomesSequenceNames}
                 myGroups={myGroups}
                 isHalfScreen={previewHalfScreen}
                 setIsHalfScreen={setPreviewHalfScreen}
-                setPreviewedSeqId={setPreviewedSeqId}
+                setPreviewedSeqId={(seqId: string | null) => setPreviewedSeqId(seqId)}
                 sequenceFlaggingConfig={sequenceFlaggingConfig}
             />
             <div className='md:w-[18rem]'>
@@ -364,7 +381,7 @@ export const InnerSearchFullUI = ({
             </div>
             <div
                 className={`md:w-[calc(100%-18.1rem)]`}
-                style={{ paddingBottom: previewedSeqId !== null && previewHalfScreen ? '50vh' : '0' }}
+                style={{ paddingBottom: Boolean(previewedSeqId) && previewHalfScreen ? '50vh' : '0' }}
             >
                 <RecentSequencesBanner organism={organism} />
 
@@ -468,7 +485,7 @@ export const InnerSearchFullUI = ({
                         }
                         selectedSeqs={selectedSeqs}
                         setSelectedSeqs={setSelectedSeqs}
-                        setPreviewedSeqId={setPreviewedSeqId}
+                        setPreviewedSeqId={(seqId: string | null) => setPreviewedSeqId(seqId)}
                         previewedSeqId={previewedSeqId}
                         orderBy={
                             {
diff --git a/website/src/components/SearchPage/SeqPreviewModal.tsx b/website/src/components/SearchPage/SeqPreviewModal.tsx
index 06b8827a7d..8f2fbb275a 100644
--- a/website/src/components/SearchPage/SeqPreviewModal.tsx
+++ b/website/src/components/SearchPage/SeqPreviewModal.tsx
@@ -115,6 +115,7 @@ export const SeqPreviewModal: React.FC<SeqPreviewModalProps> = ({
                     className={BUTTONCLASS}
                     onClick={() => setIsHalfScreen(!isHalfScreen)}
                     title={isHalfScreen ? 'Expand sequence details view' : 'Dock sequence details view'}
+                    data-testid='toggle-half-screen-button'
                 >
                     {isHalfScreen ? (
                         <MaterialSymbolsLightWidthFull className='w-6 h-6' />
@@ -126,7 +127,13 @@ export const SeqPreviewModal: React.FC<SeqPreviewModalProps> = ({
                 <a href={routes.sequenceEntryDetailsPage(seqId)} title='Open in full window' className={BUTTONCLASS}>
                     <OouiNewWindowLtr className='w-6 h-6' />
                 </a>
-                <button type='button' className={BUTTONCLASS} onClick={onClose} title='Close'>
+                <button
+                    type='button'
+                    className={BUTTONCLASS}
+                    onClick={onClose}
+                    title='Close'
+                    data-testid='close-preview-button'
+                >
                     <MaterialSymbolsClose className='w-6 h-6' />
                 </button>
             </div>
@@ -136,12 +143,20 @@ export const SeqPreviewModal: React.FC<SeqPreviewModalProps> = ({
     return (
         <Transition appear show={isOpen} as={React.Fragment}>
             {isHalfScreen ? (
-                <div className='fixed bottom-0 w-full left-0 z-40 bg-white p-6 border-t border-gray-400'>
+                <div
+                    className='fixed bottom-0 w-full left-0 z-40 bg-white p-6 border-t border-gray-400'
+                    data-testid='half-screen-preview'
+                >
                     {controls}
                     {content}
                 </div>
             ) : (
-                <Dialog as='div' className='fixed inset-0 z-40 overflow-y-auto' onClose={onClose}>
+                <Dialog
+                    as='div'
+                    className='fixed inset-0 z-40 overflow-y-auto'
+                    onClose={onClose}
+                    data-testid='sequence-preview-modal'
+                >
                     <div className='min-h-screen px-8 text-center'>
                         <div className='fixed inset-0 bg-black opacity-30' />
                         <DialogPanel className='inline-block w-full p-6 my-8 overflow-hidden text-left align-middle transition-all transform bg-white shadow-xl rounded-2xl pb-0'>
diff --git a/website/src/components/SearchPage/Table.tsx b/website/src/components/SearchPage/Table.tsx
index bb6540bd2a..2456cbf6ce 100644
--- a/website/src/components/SearchPage/Table.tsx
+++ b/website/src/components/SearchPage/Table.tsx
@@ -180,6 +180,7 @@ export const Table: FC<TableProps> = ({
                                     } cursor-pointer`}
                                     onClick={(e) => handleRowClick(e, row[primaryKey] as string)}
                                     onAuxClick={(e) => handleRowClick(e, row[primaryKey] as string)}
+                                    data-testid='sequence-row'
                                 >
                                     <td
                                         className='px-2 whitespace-nowrap text-primary-900 md:pl-6'
diff --git a/website/src/hooks/useUrlParamState.ts b/website/src/hooks/useUrlParamState.ts
new file mode 100644
index 0000000000..b5bb79b76f
--- /dev/null
+++ b/website/src/hooks/useUrlParamState.ts
@@ -0,0 +1,77 @@
+import { useCallback, useEffect, useState } from 'react';
+
+type ParamType = 'string' | 'boolean' | 'nullable-string';
+
+/**
+ * A hook that syncs state with URL parameters.
+ *
+ * @param paramName The name of the URL parameter to sync with
+ * @param queryState The current URL query state object
+ * @param defaultValue The default value to use if the parameter is not present in the URL
+ * @param setState Function to update the URL query state
+ * @param paramType Type of the parameter for proper parsing/serialization
+ * @param shouldRemove Function to determine if the parameter should be removed from URL
+ * @returns [value, setValue] tuple similar to useState
+ */
+function useUrlParamState<T>(
+    paramName: string,
+    queryState: Record<string, string>,
+    defaultValue: T,
+    setState: (callback: (prev: Record<string, string>) => Record<string, string>) => void,
+    paramType: ParamType = 'string',
+    shouldRemove: (value: T) => boolean,
+): [T, (newValue: T) => void] {
+    const [valueState, setValueState] = useState<T>(
+        paramName in queryState ? parseUrlValue(queryState[paramName], paramType) : defaultValue,
+    );
+
+    function parseUrlValue(urlValue: string, type: ParamType): T {
+        switch (type) {
+            case 'boolean':
+                return (urlValue === 'true') as T;
+            case 'nullable-string':
+                return (urlValue || null) as T;
+            case 'string':
+            default:
+                return urlValue as T;
+        }
+    }
+
+    const updateUrlParam = useCallback(
+        (newValue: T) => {
+            setState((prev: Record<string, string>) => {
+                if (shouldRemove(newValue)) {
+                    const newState = { ...prev };
+                    delete newState[paramName];
+                    return newState;
+                } else {
+                    return {
+                        ...prev,
+                        [paramName]: String(newValue),
+                    };
+                }
+            });
+        },
+        [paramName, setState, shouldRemove],
+    );
+
+    const setValue = useCallback(
+        (newValue: T) => {
+            setValueState(newValue);
+            updateUrlParam(newValue);
+        },
+        [updateUrlParam],
+    );
+
+    useEffect(() => {
+        const urlValue = paramName in queryState ? parseUrlValue(queryState[paramName], paramType) : defaultValue;
+
+        if (JSON.stringify(urlValue) !== JSON.stringify(valueState)) {
+            setValueState(urlValue);
+        }
+    }, [queryState, paramName, paramType, defaultValue, valueState]);
+
+    return [valueState, setValue];
+}
+
+export default useUrlParamState;