The Croatian despatched Frenchman Pierre-Hugues Herbert 6-3, 6-2 to move with ease into the semi-finals of the $550,000 tournament, held in the western Indian city of Pune.
Cilic, the 2014 US Open Champion, smashed seven aces as he won the quarter-final match in just over an hour.
The top seed is yet to drop a set in the hard-court event as he warms up for the year's opening Slam, the Australian Open, which starts in Melbourne on January 15.
Cilic will play Gilles Simon, 89th in the world rankings, in Pune's semi-finals after the Frenchman overcame Spaniard Ricardo Ojeda Lara 6-2, 6-3.
It was a nervy day for South African number two seed Kevin Anderson, however.
The big hitter had to come from behind to defeat Kazakhstan's Mikhail Kukushkin, ranked 74th in the ATP standings.
Kukushkin took the first set 7-6 (7/3) before Anderson bounced back to win the remaining two sets 6-4 and 6-2.
Anderson will take on France's Benoit Paire in the other semi after he also needed three sets to defeat Dutchman Robin Haase, eventually triumphing 7-5, 2-6, 6-3.