The world number six took advantage of his opponent's predilection for double faults to come through by three quarters to one.
Highlights: Stefanos Tsitsipas beats Dustin Brown to maintain Ultimate Tennis Showdown streak
In the day's other matches, Benoit Paire came from a quarter down to beat Corentin Moutet, a substitute for Lucas Pouille, 3-1, and David Goffin recorded the first whitewash of the tournament, beating Alexei Popyrin 4-0.
De Minaur celebrates winning UTS 3
Spain's Feliciano Lopez repeated the feat at the start of the evening session, beating Matteo Berrettini by the same scoreline.
Highlights: David Goffin whitewashes Alexei Popyrin at Ultimate Tennis Showdown
Tournament debutant Dominic Thiem had an evening to forget, losing to 34-year-old RIchard Gasquet, who had his famous backhand on display in a 3-1 triumph.
Watch the Ultimate Tennis Showdown on Eurosport
Highlights: De Minaur beats Gasquet to win UTS 3
'The Demon' Alex de Minaur wins Ultimate Tennis Showdown 3