diff --git a/web/components/single-line.css b/web/components/single-line.css
new file mode 100644
--- /dev/null
+++ b/web/components/single-line.css
@@ -0,0 +1,5 @@
+.singleLine {
+  white-space: nowrap;
+  overflow: hidden;
+  text-overflow: ellipsis;
+}
diff --git a/web/components/single-line.react.js b/web/components/single-line.react.js
new file mode 100644
--- /dev/null
+++ b/web/components/single-line.react.js
@@ -0,0 +1,25 @@
+// @flow
+
+import classNames from 'classnames';
+import * as React from 'react';
+
+import { firstLine } from 'lib/utils/string-utils.js';
+
+import css from './single-line.css';
+
+type Props = {
+  +children: string,
+  +className?: string,
+};
+
+function SingleLine(props: Props): React.Node {
+  const { children, className } = props;
+
+  const text = firstLine(children);
+
+  const singleLineClassName = classNames([css.singleLine, className]);
+
+  return <div className={singleLineClassName}>{text}</div>;
+}
+
+export default SingleLine;
diff --git a/web/modals/user-profile/user-profile.css b/web/modals/user-profile/user-profile.css
--- a/web/modals/user-profile/user-profile.css
+++ b/web/modals/user-profile/user-profile.css
@@ -15,7 +15,8 @@
 }
 
 .usernameContainer {
-  padding-left: 16px;
+  margin-left: 16px;
+  overflow: hidden;
 }
 
 .usernameText {
diff --git a/web/modals/user-profile/user-profile.react.js b/web/modals/user-profile/user-profile.react.js
--- a/web/modals/user-profile/user-profile.react.js
+++ b/web/modals/user-profile/user-profile.react.js
@@ -14,6 +14,7 @@
 import UserProfileAvatarModal from './user-profile-avatar-modal.react.js';
 import css from './user-profile.css';
 import UserAvatar from '../../avatars/user-avatar.react.js';
+import SingleLine from '../../components/single-line.react.js';
 
 type Props = {
   +userInfo: ?UserInfo,
@@ -65,7 +66,7 @@
             <UserAvatar userID={userInfo?.id} size="L" />
           </div>
           <div className={css.usernameContainer}>
-            <div className={css.usernameText}>{usernameText}</div>
+            <SingleLine className={css.usernameText}>{usernameText}</SingleLine>
             <div
               className={css.copyUsernameContainer}
               onClick={onClickCopyUsername}