Sharapova won her 11th straight match without losing a set, a streak that includes her victory at Indian Wells two weeks ago. She improved to 7-1 in her career against Jankovic.
It will be the fifth Sony Open final for Sharapova, but she has never won the tournament.
Williams remained perfect in her meetings with Radwanska, winning for the fifth time in as many matches. Williams claimed 26 of the first 39 points in the match.
Williams and Sharapova have met 13 times and Sharapova has won just twice, both of those victories coming in 2004. Williams has a 10-match winning streak working against Sharapova and has won this event five times.