Justin Theroux and his fiancée Nicole Brydon Bloom appear to have finally tied the knot ... 'cause the two had a romantic photo shoot on the beach in what looks like a wedding dress and matching tuxedo.

The actors were down in Tulum, Mexico this weekend ... and, they ran out to the sandy beach for a sweet photo sesh.

Check it out ... the two are posing for a series of couples photos, as well as solo shots -- with the wind whipping Nicole's dress around and Justin leaning in to smooch his better half's neck.

It certainly looks like a wedding shoot ... and, we have it on good authority that the two did in fact take the plunge. We've reached out to Justin's team for more details.

Justin and Nicole were first linked romantically back in 2023 ... and, People broke the news that the two were engaged back in August.

In January, photographers got the two in Tulum ... unclear if they were scoping out venues or just on vacay -- but, it seems they have an affinity for the area.

Justin has been married once before ... surprising fans by tying the knot with actress Jennifer Aniston seemingly out of the blue in 2015. They separated in 2018 and later divorced.