Tekken X Street Fighter was announced on July 24, 2010 at the 2010 San Diego Comic-Con along with the Capcom-produced Street Fighter X Tekken. The gameplay of Tekken X Street Fighter will be featuring the same 3D fighting game engine of the Tekken franchise as opposed to Street Fighter X Tekken which features the 2D styled gameplay of Street Fighter IV. The game is planned to be released for the PlayStation 3 and Xbox 360 consoles. Ryu and Jin Kazama appear on the game's promotional poster (shadowed by their alter-egos "Evil Ryu" and "Devil Jin" respectively). It was still in its early stages of development and no images or videos were released at the 2010 Comic-Con. Katsuhiro Harada did reveal some concepts at gamescom 2010 such as a prototype model of Ryu, with the gi of Tekken's Paul Phoenix. He said the team has yet to finish the model as details and lighting were not completed.
This is not the first time Namco and Capcom have made a game together as they released a Japan-only crossover game in 2005 for the PlayStation 2 titled Namco × Capcom. However, this game consisted of characters outside of the Street Fighter universe as well as the Tekken universe and instead included various characters from Capcom and ones from Namco (like the Darkstalkers and Soul series, for example), and at least two characters exclusive to the game. Namco × Capcom was a role playing game, thus making Tekken X Street Fighter and Street Fighter X Tekken the first games in the fighting game genre to be made by Namco and Capcom.
On March 4, 2012, Namco released a poll on the TekkenFacebook page asking fans to vote for who they would like to see on Tekken X Street Fighter's roster. There were 55 Tekken characters and 66 Street Fighter characters to choose from, and fans were able to choose five of their favorites from each series. On March 7, 2012, Tekken producer Katsuhiro Harada clarified that the poll will not decide the final roster, but will instead be used in conjunction with various research methods to determine the character lineup. In April 2012, Harada stated that the game was about 10% complete. At the 2014 San Diego Comic Con International, Harada revealed that the game is still in development; the reason for the scarce information is due to Bandai Namco waiting for the opportunity to market it.
As of January 21st, 2015, 40 staff members from Bandai Namco are working on the game.