Mel B Marries Hairstylist Rory McPhee in London Ceremony

Mel B and Rory McPhee are "2 Become 1" ... tying the knot in a star-studded London ceremony!

The singer-songwriter and her hairstylist better half got married at St. Paul's Cathedral in England's capital Saturday ... with Mel B outfitted in a gorgeous white beaded dress, complete with a veil.

She and Rory -- who was wearing a traditional kilt -- smooched on the steps of the church ... looking like they were ready for the rest of their lives.

According to People ... Mel B wore a custom gown from Josephine Scott during her wedding ceremony, later changing into a Justin Alexander gown.

Emma Bunton -- aka Baby Spice -- Cara Delevingne, Daisy Lowe, Katherine Ryan and many more bold-faced names were in attendance.

Unclear if Victoria Beckham made it out to the wedding ... but, she posted in honor of her longtime bandmate to congratulate her on the marriage.

This is Mel's third marriage ... she was previously tied to dancer Jimmy Gulzar from 1998 to 2000 and producer Stephen Belafonte from 2007 to 2017. Her three children served as her bridesmaids on Saturday.

Mel and Rory got engaged way back in 2022 ... and, it's believed they've been dating since 2018.