The duo overcame third seeds Oliver Marach and Philipp Oswald 6-3, 6-4 to secure their victory over 77 minutes.
The Britons were playing together for the first time since they reached the quarter-finals in Sofia last year.
It is the second title O’Mara and Skupski have won together at all levels, after triumphing at an ATP Challenger Tour event in Mouilleron Le Captif in 2018.
“I feel good,” O’Mara, who hails from Arbroath, said. “It has been a long time [since I won a title] and you start to question your level a little bit. It is great to be able to get that title and know this is the level you can compete at. To share this with Ken is class.
“It is not often you get to play doubles with someone who you really like, so to have a big moment with Ken was the best feeling I have had on court maybe ever."
Elsewhere, British number two Cameron Norrie reached the final of the San Diego Open after coming from behind to defeat top seed Andrey Rublev 3-6, 6-3, 6-4.
Speaking in an on-court interview broadcast by Amazon Prime Video, Norrie said: "What an incredible match.
"This is such a big win for me, I am good friends with Andrey so it is not easy playing against him. It is definitely a match I will remember for a long time."
Norrie is due to face Norwegian second seed Casper Ruud in the final in the early hours of Monday morning.