Stevens is being released by Kent at the end of the season, although he still harbours hopes of a move to another county.
Stevens made an unbeaten 33 in Kent's 306-6, having been greeted with a standing ovation from the crowd.
Kent then defended that total by dismissing Lancashire for 285 to win by 21 runs and end a sequence of eight consecutive losses in one-day finals since the club lifted the now defunct Benson and Hedges Cup back in 1978.
While there was plenty of sympathetic applause for Stevens, uncapped by England despite a prolific career at county level that started with Leicestershire in 1997, it was a player at the other end of the age spectrum who was the star of the show on Saturday.
Joey Evison (20), all-rounder playing on what is still his home ground ahead of his permanent move from Nottinghamshire to Kent next season, scored a brilliant 97 and took 2-34.
Former England batsman Joe Denly backed up Evison's efforts with an innings of 78 from just 69 balls before the Kent new-ball duo of Grant Stewart and Nathan Gilchrist took three wickets each.
Lancashire captain Keaton Jennings and experienced all-rounder Steven Croft both made 72 but their efforts were not enough to give the Red Rose a 12th one-day final victory.