Fritz, seeded third in the 500-level hard court tournament, needed five match points to subdue the 24th-ranked teen and capture his 11th title, and his first since Eastbourne last year.
After seizing control in the first-set tiebreaker, Fritz roared to a 3-0 lead with a pair of service breaks in the second.
He gave back a break in the fourth game with a double fault on break point, and Jodar climbed out of a 0-30 hole to hold serve and narrow the gap to 3-2.
But Jodar couldn't find another break. He held for 5-4 to force Fritz to serve it out, the American's chance delayed just slightly as Jodar had treatment on his left wrist after taking a tumble in the ninth game.
The final game was a slugfest. Fritz squandered a pair of match points at 40-15 and gave himself another with a booming forehand.
Jodar fought off two more match points before earning a break point that Fritz saved with another forehand winner.
Fritz finally got the job done after one hour and 49 minutes, Jodar misfiring on a pair of forehands to bring it to a close.
Fritz, who was playing his third final of the season, collapsed to the court when it was done before rising to salute the crowd.
The contest was postponed from Sunday after heavy rain halted the WTA final between Jessica Pegula and Alexandra Eala.
Jodar missed out on a second ATP title, after winning in Morocco in April. But by reaching the final he's assured of reaching a career-high 15th in the rankings.