He was a 41%-owner of id until he left the company in 2005. At the time the press was told he felt he had done all he could do in the gaming field and was planning to pursue his passions of art. However, in September 2005, The Wall Street Journal revealed he was taking his former business partners to court claiming he was effectively fired by them in an attempt to force him to sell his 41% stake in the company for $11 million under the terms of a contract he wants the court to nullify. $11 million is thought to be a fraction of the true value of his stake, which is thought to be closer to $43 million after the company received a $105 million bid from Activision in 2004.
Carmack has also been credited for coining the term "gibs".
In September 2014, Carmack was revealed as the new owner of the five-star Heritage Golf & Spa Resort in Killenard, Ireland.
In April 2016, it was reported that Carmack had reunited with Romero under a new Galway, Ireland-based start-up, The Night Work Games, to produce a new video game, Blackroom, for which they had launched a crowdfunding campaign on Kickstarter. The game has been described as "a return to fast, violent and masterful play on the PC". Later the campaign was put on hold to allow Carmack and Romero time to complete a working demo of the game. According to the two developers, their decision was based on players' feedback regarding the playability of the demo. The company behind Blackroom, Night Work Games, was seeking $700,000 to fund the development of the game. Before being put on hold, the campaign had raised $131,052 from its supporters.