Barca are aiming to become European champions for the third season running in Saturday's (24.05.25) showpiece in Lisbon and the midfielder says her team must be wary of a Gunners team who pulled off an outstanding comeback against Lyon in the semi-finals.
Bonmati told ESPN: "For me, it was a surprise Arsenal reaching the final.
"They absolutely deserve it, because scoring four goals against Lyon in the second leg is not easy at all.
"I congratulate them for that because I think it was a big surprise, but a well deserved one."
Barca will face Arsenal in a competitive match for the first time since 2021 in the final and the two-time Ballon d'Or winner says the game will have a "different feel" for her team.
The Spain international said: "It's a final with a different feel because we've never played Arsenal in a final. It's been a few years since we even played them. For that reason, it's a new challenge for us, being able to play a different team."
Barcelona could win a quadruple this season but Bonmati explained that European glory is the prize that everybody at the club strives for.
She said: "For the club, the Champions League is the top priority. Of course we have Liga F, the Supercopa and the Copa, but it's clear that the Champions League is the most important trophy for us.
"I always say it's the competition that excites me the most when the season starts. We're competing more both as a team and on an individual level, which takes you to another dimension.
"It's where you can most test yourself and compete because you're up against the best players, which shows you what level you're at."