diff --git a/lib/package.json b/lib/package.json
--- a/lib/package.json
+++ b/lib/package.json
@@ -42,6 +42,7 @@
     "fast-json-stable-stringify": "^2.0.0",
     "file-type": "^12.3.0",
     "focus-trap-react": "^10.1.4",
+    "idna-uts46-hx": "^2.3.1",
     "invariant": "^2.2.4",
     "just-clone": "^3.2.1",
     "lodash": "^4.17.21",
diff --git a/lib/shared/markdown.js b/lib/shared/markdown.js
--- a/lib/shared/markdown.js
+++ b/lib/shared/markdown.js
@@ -347,6 +347,8 @@
   );
 }
 
+const ensRegex: RegExp = /^[a-zA-Z0-9-]{3,}\.eth$/;
+
 export {
   paragraphRegex,
   paragraphStripTrailingNewlineRegex,
@@ -372,4 +374,5 @@
   stripSpoilersFromNotifications,
   stripSpoilersFromMarkdownAST,
   parseChatMention,
+  ensRegex,
 };
diff --git a/lib/utils/ens-helpers.js b/lib/utils/ens-helpers.js
--- a/lib/utils/ens-helpers.js
+++ b/lib/utils/ens-helpers.js
@@ -1,7 +1,9 @@
 // @flow
+import uts46 from 'idna-uts46-hx';
 
 import { ENSCache } from './ens-cache.js';
 import { getETHAddressForUserInfo } from '../shared/account-utils.js';
+import { ensRegex } from '../shared/markdown.js';
 
 type BaseUserInfo = { +username?: ?string, ... };
 export type GetENSNames = <T: ?BaseUserInfo>(
@@ -70,4 +72,27 @@
   });
 }
 
-export { getENSNames };
+function isValidENSName(name: string): boolean {
+  // While the Ethereum spec allows for more flexibility in ENS names
+  // (see https://eips.ethereum.org/EIPS/eip-137#name-syntax), we want to only
+  // perform lookups on names that adhere to two specific rules:
+  // 1. TLD should be .eth
+  // 2. SLD should be at least three characters in length
+  // Here, we enforce these rules and also use a library similar to the one
+  // reccomended by the Ethereum spec to perform the 'heavy lifting' of
+  // making sure the name adheres to all of the specific limitations.
+  try {
+    // Ethereum spec guidelines
+    const convertedName = uts46.toAscii(name, {
+      transitional: false,
+      useStd3ASCII: true,
+    });
+
+    // Our specific rules on TLDs and SLDs
+    return !!convertedName.match(ensRegex);
+  } catch (e) {
+    return false;
+  }
+}
+
+export { getENSNames, isValidENSName };
diff --git a/lib/utils/ens-helpers.test.js b/lib/utils/ens-helpers.test.js
new file mode 100644
--- /dev/null
+++ b/lib/utils/ens-helpers.test.js
@@ -0,0 +1,31 @@
+// @flow
+
+import { isValidENSName } from './ens-helpers.js';
+
+describe('it should correctly validate ENS names', () => {
+  it('should match all valid ENS names', () => {
+    expect(isValidENSName('foo.eth')).toBe(true);
+    expect(isValidENSName('jack.eth')).toBe(true);
+    expect(isValidENSName('thisuserhasareallylongname.eth')).toBe(true);
+    expect(isValidENSName('hello-world.eth')).toBe(true);
+  });
+
+  it('should not match any SLDs less than 3 characters', () => {
+    expect(isValidENSName('fo.eth')).toBe(false);
+    expect(isValidENSName('f.eth')).toBe(false);
+    expect(isValidENSName('')).toBe(false);
+    expect(isValidENSName('a.eth')).toBe(false);
+  });
+
+  it('should not match any TLDs other than .eth', () => {
+    expect(isValidENSName('foo.com')).toBe(false);
+    expect(isValidENSName('foo.')).toBe(false);
+    expect(isValidENSName('foo')).toBe(false);
+  });
+
+  it('should not match any names with special characters', () => {
+    expect(isValidENSName('foo.eth!')).toBe(false);
+    expect(isValidENSName('foo.eth#')).toBe(false);
+    expect(isValidENSName('foo$.eth')).toBe(false);
+  });
+});