The hip hop world had high expectations for the track, which was premiered on LA's Power 106 before being uploaded to Soundcloud by TDE.
'i' was produced by Rahki and is very different from anything on Good Kid, with a groovier feel and spiralling bass lines and a chorus in which Kendrick declares 'I love myself'.
Earlier in the week he teased the artwork for the single (above), depicting members of the Bloods and Crips street gangs apparently in unity.
The track could end up featuring on Kendrick's next album, which doesn't yet have a release date but he previously suggested could be ready by the end of the year.
He hasn't yet sorted any guest verses for it but says it probably won't feature many anyway.
"I have so much to say," he told Rolling Stone. "It’s almost selfish of me."
Given that this track feels standalone, the new album might depart from the narrative-style of Good Kid.Reuse content