The pop star, 28, and her sailor beau exchanged vows on Thursday (17Jan13).
The wedding news was confirmed by Donaghy's bandmate Keisha Buchanan, who posted a shot from the nuptials on Instagram hours after the intimate ceremony.
Buchanan, who is now the new bride's bandmate in Sugababes spin-off band Mks, wrote, "The most beautiful bride I've ever seen! Siobhan I'm so proud of u, Love u 2 bits! Chris ur amazing! Mr & Mrs MCCoy!"
The wedding comes just two weeks after Mks performed their first gig together for almost a decade on New Year's Eve (31Dec12). The former Sugababes reunited last year (12).