Sulu was initially assigned as a physicist aboard the Enterprise - NCC1701 -  in 2265, but later transferred to the helm.
He had a wide range of hobbies including botany and fencing. The latter manifested itself in 2266 when, suffering from the effects of the Psi 2000 virus, he threatened everyone he encountered with a foil. Old style handguns were also another of Sulu's interests, and he always wanted a Police Special as part of his collection.

Sulu had a daughter, Demora Sulu, who was born in 2271.

He took command of the starship Excelsior in 2290 where he began a 3 year scientific mission to catalogue gaseous planetary anomalies in the Beta quadrant. Sulu and the Excelsior played a pivotal role in the historic Khitomer peace conference of 2293, by helping to protect the conference against Federation and Klingon forces intent on disrupting the peace process.
During the incident, Sulu displayed his loyalty, and his courage, when attempted the rescue of former crew mates James Kirk and Leonard McCoy against Starfleet orders. During the attempted rescue, Sulu narrowly escaped a Klingon patrol commanded by Captain Kang in the Azure Nebular. The incident was never entered into his official log.

To honour Sulu's contribution to space exploration, his portrait is displayed in Starfleet headquarters in San Francisco.