Berkshire suffered a catastrophic second innings collapse to hand Devon a 10 wicket win at Sidmouth and the Minor Counties Western Division title.
Trevor Anning and Scott Barlow each took three wickets as Berkshire were bowled out for 107 as ex-England spinner Shaun Udal top scored with 21.
Rob Holman and James Burke made Devon's target of 23 in two-and-a-half overs.
They will now play the winners of the Eastern Division in the final from September 4-7.
Earlier Devon had ended their first innings on 364 for 8 as Burke (75) and Holman (52) put on 115 for the first wicket and Matthew Thompson hit 60 not out.