The "American Horror Story" star, 57, was rumoured to have parted ways with actress Maggie in late February, four years after the couple announced plans to wed.
However, McDermott appears to have since bounced back from the break-up with a little help from Beck, with whom he was recently photographed strolling hand-in-hand in the Los Angeles neighbourhood of Venice, reports The Blast.
The actor has yet to comment on the nature of his relationship with Beck.
Prior to finding love with Maggie on the set of their TV show "Stalker" in 2014, he was married to another actress, Shiva Rose, from 1995 to 2009. The former couple shares daughters Colette and Charlotte.