iOS 5.1 was released in March 2012 and was the first version of Apple's emoji font to use cross-platform compatible emoji codepoints from the Unicode Standard. Previous releases of iOS supported emoji characters in the private use area of Unicode.

Support for a number of new emojis was available in this release, but not these new emojis were not displayed on the iOS emoji keyboard. As such, widespread use of emojis from Unicode 6.0 was not achieved until the release of iOS 6.0 later in 2012.

Emojis in this release were also supported in Mac OS X 10.7.4 and above.