Ken and Ryu, along with former final boss Sagat, would be the only characters from the original Street Fighter to return in the game's true sequel, Street Fighter II, first released in 1991. In Street Fighter II, Ken is invited to participate in the World Warrior tournament by Ryu, with Ken having already moved away from Japan to live in America. In Ken's ending, he ends up marrying his girlfriend Eliza. Street Fighter II was a breakaway hit for Capcom, leading to the production of revised editions of the same game which included Champion Edition and Hyper Fighting in 1992, Super Street Fighter II in 1993 and Super Turbo in 1994, which all follow the same plot. Numerous spinoff products were made as well during the game's popularity: when Capcom licensed Hasbro to produced a line of action figures, Capcom were forced to give Ken the surname "Masters" to distinguish the character from Mattel's Ken Carson character from the Barbie toyline. The full name Ken Masters would be used in the animated Street Fighter II movie and in the Street Fighter II V series before being canonized in the games.
An all-new Street Fighter game would not be released until 1995, Street Fighter Alpha was released. Plotwise, the game is a prequel to the Street Fighter II games which fleshed out the established Street Fighter II characters, as well as reintroduced characters from the original Street Fighter and the beat-em-up Final Fight. Alpha features a younger Ken, who is searching for Ryu, having recently won the first "World Warrior" tournament in the events of the original Street Fighter. In Ken's ending in the original Street Fighter Alpha, he defeats Ryu and heads back to America, where he meets his future girlfriend and wife Eliza. Street Fighter Alpha would be followed by its own line of sequels: Street Fighter Alpha 2, which follows the same plot as in the original Alpha (with a revised ending for Ken); and Street Fighter Alpha 3, which takes place after the events in the first two games. In Alpha 3, Ken is featured in the numerous characters' storylines within the game.
Street Fighter III (released in 1997), features an older Ken, who is now married to Eliza and has a son with her named Mel. He also takes a young student named Sean under his wing. Street Fighter III was followed by 2nd Impact released during the same year and 3rd Strike in 1999.
Ken, along with Ryu, are seen sparring with each other in the trailer to the upcoming Street Fighter IV. Ken was confirmed as a playable character for Street Fighter IV on December 6, 2007. The story of IV will be set between Street Fighter II and III.
In Ken's ending of Street Fighter IV, it is shown that Ken and Eliza are expecting their first child.
Outside the mainstream Street Fighter games, Ken appears in 3D form in the Street Fighter EX games, in his Alpha incarnation in X-Men vs. Street Fighter, Marvel Super Heroes vs. Street Fighter and Marvel vs. Capcom 2: New Age of Heroes and in a new form based on his Street Fighter II incarnation in Capcom vs. SNK and Capcom vs. SNK 2. He also appears in the arcade game Street Fighter: The Movie produced by Incredible Technologies, which Capcom later adapted for the home console market, and in SNK vs. Capcom: SVC Chaos by SNK Playmore, where he has an alter-ego named Violent Ken.
With the advent of "mirror matches" (same character vs.) in Street Fighter II': Champion Edition, the designers began to vary the playing styles of Ryu and Ken a bit. Ryu was given a stronger, faster Hadouken and a one-hit knockdown Tatsumaki Senpuukyaku, while Ken was given a wider arcing Shoryuken and a multi-hit Tatsumaki Senpuukyaku (In the "Marvel vs Capcom" series, the Tatsumaki Senpuukyaku went on an angle, making it effective against airborne opponents). In Super Street Fighter II, Ken began deviating from Ryu further being given a multi-hit flaming Shoryuken. In the next SFII installment, Super Street Fighter II Turbo, Ken was given the super combo Shouryuu Reppa (which was simply Ken's Jab and Strong Dragon Punches chained together) and a number of different command kicks, plus a new jumping Forward and a Knee Bash hold. These command kicks would be incorporated as the standard move list in the Street Fighter Alpha series, but remain commands in all others.
Ken mainly focuses on the Shoryuken move, to the point where his Shoryukens set the opponent on fire. Ken's Tatsumaki Senpuukyaku does not allow him to dodge projectiles at the start of the spin, but spins faster, allowing him to hit his opponent up to five times (without knocking down). Ken's Hadouken attacks are less concentrated than Ryu's, but Ken's Shoryuken has more range and does more damage than Ryu's.
By Street Fighter III, Ken has two Shōryūken Super Arts (Shōryū-reppa and Shinryūken) and Shippu Jinrai Kyaku, and in Street Fighter EX 3, he has a "meteor combo" (a Level 3 super-combo) called Kuzūryu-reppa, a mix of his other three Super Arts. Kuzūryu-reppa would be seen again in SVC Chaos: SNK vs. Capcom with it being one of Violent Ken's supers this time.
Ken's super moves consist of the Shōryū-reppa ("Rising Dragon Destroyer"), in which Ken does two or three Shōryūken; the Shinryūken ("Divine Dragon Fist"), a spinning vertical Shoryuken that lacks range, but does greater damage and more hits, especially if the kick buttons are pressed rapidly; and the most recent addition to his move-list since Street Fighter III — the Shippū Jinrai Kyaku ("Hurricane Thunderclap Leg"), which Ken does a flurry of kicks before ending with a vertical Tatsumaki-Senpū-Kyaku (or a diagonally-vertical Tatsumaki-Senpū-Kyaku in some incarnations).
It is implied in SVC Chaos: SNK vs. Capcom that Ken possesses the Orochi bloodline and Violent Ken is a manifestation of this, much like the SNK characters Iori, Yamazaki and Leona.
However, Violent Ken also used purple flames instead of regular ones in his Shoryuken, which is a feature of Akuma's Gou Hadoken and Gou Shoryuken from the Marvel vs. Capcom series, and a pillar of energy appeared at the end of his Exceed move, which is a feature of Rugal's DMs from The King of Fighters series.
Ken and Ryu are forced to betray the vengeful GNT news-crew (Chun Li, Balrog and Honda) in order to gain Bison's trust but later try to free them and are captured. When Guile eventually infiltrates Sagat's base and chaos ensues Ryu and Ken try to help free the hostages but split up when the AN forces arrive (according to Ken the soldiers get paid and that they should not risk their lives). Ken later comes to Ryu's aid when he is ambushed by Vega and Sagat. While Ryu defeats Vega, Ken defeats Sagat and drops a heavy golden statue on his hands parting him with the line: "If I hadn't met you, I might have become you."
Interestingly Ken and Sagat are portrayed as rivals, switching the usual scenario from the games where Ryu and Sagat are rivals, with Ryu's rivalry switched to Vega.