The result sends the Pumas through to a second-round match against Sounders 2 next Wednesday at Starfire Stadium in Tukwila.
Kitsap jumped ahead in the fourth minute, increased it to 3-0 by halftime, and eventually to 5-0. The Pumas got two goals each from Joe Masumiya and Carlos Patino and one from Jake Bond.
Tacoma got on the board with a close-range goal from Steven Wright in the 76th minute and a 20-yard free kick from Pedro Millan in the 88th.
Tacoma 253 was formed in January as a member of the National Premier Soccer League, while Kitsap is an established Premier Development League power and defending Western Conference champion.
Seattle Sounders FC and other Major League Soccer teams join the tournament in the fourth round at the middle of June.
Final: Kitsap 5, Tacoma 2. Pumas will meet Sounders 2 a week from tonight at Starfire in second round of the U.S. Open Cup.
88' GOAL Tacoma. 20-yard free kick -- quality at any level -- from Pedro Millan. Kitsap, 5-2.
76' GOAL Tacoma. Steven Wright gets 253 on the board from close in front of goal. Kitsap, 5-1.
Attendance: Estimated at 300.
54' GOAL Kitsap. Patino with his second. Pumas, 5-0.
48' GOAL Kitsap. Jake Bond finishing a corner kick. Pumas, 4-0.
HT: Kitsap 3, Tacoma 0. #USOC2015 Pumas dominating, but not as one-sided as score. They have finished, while 253 hasn't.
39' GOAL Kitsap. Long pass to Masumiya, who gets second goal of game. Pumas, 3-0.
34' GOAL Kitsap. Nice through ball by Ramos for second assist. Carlos Patino jukes charging keeper and finishes into emty net. Pumas, 2-0.
4' Joe Masumiya puts Kitsap ahead early, 1-0, after cross from Mike Ramos.
Pregame: It's FC Tacoma 253 hosting the Kitsap Pumas tonight at Mount Tahoma Stadium, in the first round of the U.S. Open Cup.
The winner goes on to meet Sounders 2 next Wednesday at Starfire.