The 21-year old striker who is on loan from Dundee until the end of the season tore Arbroath's Angus rivals apart with an outstanding performance which totally demoralised the visitors.
Arbroath started brightly and deservedly took the lead in the seventh minute, Swankie firing low into the net from 12 yards after being set up by Kevin Kevin McMullan.
The home side continued to press and Steven Rennie came close with a header while Paul Watson had a 25-yard blockbuster brilliantly saved by Sandy Wood.
Barry Donnachie then twice saved Montrose within 60 seconds, firstly blocking a John Voigt effort then clearing a Robbie Raeside shot off the line.
Swankie fired Arbroath further ahead in the 34th minute, expertly finishing from 15 yards after again being put through by McMullan.
Swankie completed his hat-trick two minutes later when he volleyed home a perfect Marc McCulloch cross from the left.
Tempers flared early in the second half and referee McKendrick had to break up a melee involving 14 players which ended with bookings for Ian Dobbins and Greig Henslee.
Voigt should have made it 4-0 in the 56th minute but somehow screwed his shot wide of the target when presented with an open goal.
Montrose were reduced to 10 men in the 64th minute when Donnachie was sent off for a bad foul on Swankie.
Henslee had a great chance to pull one back on 69 minutes but turned his effort narrowly past Mark Peat's left-hand post.
Voigt had another chance a few minutes before the final whistle but his header from four yards hit the face of the bar and was cleared.