The 24-year-old smashed 13 sixes to cross 100 runs in just 45 balls and led his side to an eight-wicket victory in Hamilton.
Levi's signing came after the withdrawal of Francois du Plessis. Du Plessis, who plays for Chennai Super Kings, was called up to the South African A side for the visit of Sri Lanka.
Du Plessis was first signed by Somerset after Chris Gayle cancelled his contract to revive his West Indies career.
Levi is a success in T20 career of 876 runs at an average of 31.28, and strike-rate of 148.22 in 37 matches.