Swiss third seed Wawrinka, the 2015 title winner, has not lost a set on his way to a third successive semifinal in Paris.
The 32-year-old is the oldest man to make the last four at Roland Garros since Jimmy Connors in 1985.
He will face world number one Andy Murray for a place in the final.
"It was perfect today, I'm very satisfied," said Wawrinka who will be playing in his third successive Roland Garros semifinal.
"I played well, was very solid and took my opportunities."
Wawrinka, the reigning US Open champion, took his record over Croatian seventh seed Cilic to 12-2 with an eighth successive win over the 28-year-old.
Cilic is still to beat a top five player on clay.