The way Lennon told the story of "Instant Karma," was "I wrote it for breakfast, recorded it for lunch and we're putting it out for dinner." Many fans feel it was one of his best songs as a solo artist. It was the third Lennon single to appear before the official breakup of the Beatles. The only exaggeration in John's description was the part about dinner: "Instant Karma" wasn't actually released to the public until 13 days after it was written and recorded over the course of a single Tuesday, on January 27, 1970. By any measure, it was one of the fastest pop songs ever to come to market.

The January 27 session came about spontaneously. Lennon wrote the song that morning and said, "I knew I had a hit record." What got the record finished that same day and gave it its amazing sound, however, was the unannounced appearance of Phil Spector that evening in the EMI studios. After several run-throughs under Spector's direction, John said, "Suddenly we went in the room and heard what he'd done to it...it was fantastic. It sounded like there was fifty people playing." John's happiness with the results would lead directly to Spector's taking over the dormant Let it Be project—a development that ended up driving a further wedge between Lennon and McCartney prior to the official breakup of the Beatles.