Beck has penned a two-year deal at Huish Park after agreeing terms this morning.
The 6ft 5in striker joins the Glovers having spent his professional career at Carlisle United where he racked up over 60 appearances scoring 12 goals.
During his spell at Carlisle, Beck spent time on loan at Workington and last season spent time north of the border at Falkirk.
At Falkirk Mark made 20 appearances in all competitions, scoring five times.
Manager Paul Sturrock said: “I have watched Mark from afar for a while now. He had a successful loan spell at Falkirk last season and managed to force himself into the Scotland Under21 squad.
“He has great talent, he is a big lad at six foot five. I am hoping with that kind of target man and the pace we have, we now have someone who will give us an out ball should we need it.”