The Serb world number one will face either Roger Federer or Stanislas Wawrinka in Sunday's final at the Foro Italico where he will be bidding for a fourth Rome Masters title.
The Swiss rivals play later.
In the women's tournament there was better fortune for a Spanish player with Carla Suarez Navarro beating Romania's Simona Halep 2-6 6-3 7-5 to reach her ninth career final.
Djokovic's winning streak now stands at 21, but he has been forced to earn them this week with closely fought victories over Nicolas Almagro, Thomaz Bellucci and Kei Nishikori.
He seemed to move up a level against Ferrer though with a clinical display. The top seed needed just two breaks of serve to clinch a ninth consecutive win over Ferrer.
"I played the best match of the week," Djokovic told Sky Sports Italia. "I'm satisfied with the way I played and happy to be in another final in Rome."
Djokovic's only frustration was the state of the Centrale court, repeatedly complaining about the condition of the clay.
"That's the one thing I could have handled better. I should've been less nervous as there was nothing I could do about the court," he said.
Suarez Navarro is the form player on the WTA Tour this year with 31 wins but she was two points away from losing in the 10th game of the final set before turning snatching the win.
"It was such a tough match from a physical standpoint," Suarez Navarro told SuperTennis TV. "The biggest improvement I've made this year is in my mind."
She took advantage of Halep's inconsistency on her forehand to get over the line on her third match point.
Russians Maria Sharapova, the two-time champion, and qualifier Daria Gavrilova play in the second semi-final later.

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