diff --git a/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap b/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
index 16ec0a6e8a..da99964c24 100644
--- a/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
+++ b/packages/docusaurus-utils-validation/src/__tests__/__snapshots__/validationSchemas.test.ts.snap
@@ -60,4 +60,4 @@ exports[`validation schemas RemarkPluginsSchema: for value=false 1`] = `"\\"valu
 
 exports[`validation schemas RemarkPluginsSchema: for value=null 1`] = `"\\"value\\" must be an array"`;
 
-exports[`validation schemas URISchema: for value="invalidURL" 1`] = `"\\"value\\" does not match any of the allowed types"`;
+exports[`validation schemas URISchema: for value="spaces are invalid in a URL" 1`] = `"\\"value\\" does not match any of the allowed types"`;
diff --git a/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts b/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
index 4045a838e0..88bab0fa4a 100644
--- a/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
+++ b/packages/docusaurus-utils-validation/src/__tests__/validationSchemas.test.ts
@@ -111,12 +111,16 @@ describe('validation schemas', () => {
   test('URISchema', () => {
     const validURL = 'https://docusaurus.io';
     const doubleHash = 'https://docusaurus.io#github#/:';
-    const invalidURL = 'invalidURL';
+    const invalidURL = 'spaces are invalid in a URL';
+    const relativeURL = 'relativeURL';
+    const relativeURLWithParent = '../relativeURLWithParent';
     const urlFromIssue = 'https://riot.im/app/#/room/#ligo-public:matrix.org';
     const {testFail, testOK} = createTestHelpers({schema: URISchema});
     testOK(validURL);
     testOK(doubleHash);
     testFail(invalidURL);
+    testOK(relativeURL);
+    testOK(relativeURLWithParent);
     testOK(urlFromIssue);
   });
 });
diff --git a/packages/docusaurus-utils-validation/src/validationSchemas.ts b/packages/docusaurus-utils-validation/src/validationSchemas.ts
index 4e2d57dac1..d4cee25f1c 100644
--- a/packages/docusaurus-utils-validation/src/validationSchemas.ts
+++ b/packages/docusaurus-utils-validation/src/validationSchemas.ts
@@ -26,7 +26,7 @@ export const RehypePluginsSchema = MarkdownPluginsSchema;
 export const AdmonitionsSchema = Joi.object().default({});
 
 export const URISchema = Joi.alternatives(
-  Joi.string().uri(),
+  Joi.string().uri({allowRelative: true}),
   Joi.custom((val, helpers) => {
     try {
       const url = new URL(val);