The Russian is still seeking her first victory in the event after finishing runner-up on four previous occasions.
Sharapova broke Jankovic three times in each set to win her 11th match in a row, ending matters after 63 minutes by breaking the Serb with a forehand winner.
The third seed reduced the number of double faults from 14 in a quarter-final victory over Italy's Sara Errani to only three against Jankovic.
"I thought I needed to step it up a lot from my last match," Sharapova said. "I had a very tough opponent and I had to play much better. I was very happy at the way I was able to focus today [Thursday]."
She will now meet Serena Williams, who was similarly untroubled against fourth seed Agnieszka Radwanska, taking precisely one minute more than Sharapova to complete a 6-0 6-3 win.
Williams will go into the final, her 8th in Miami, a strong favourite having won each of her last 10 meetings with the Russian, dropping just two sets in the process.