The 24-year-old Italian star had to battle hard though before prevailing in two tie-breaker sets - 7-6 (8-6) 7-6 (7-4) - with a polished display in Sunday's final under the California desert sun.
He joined greats Novak Djokovic and Roger Federer in completing.the coveted set of six titles.
Furthermore, with his first title of the year, he became the first player since 1990 to win consecutive Masters 1000 titles without dropping a set and extended his winning streak in this category to 11 matches, dating back to his Paris title last November.
World No.2 Sinner was imperious throughout the final against the in-form Medvedev - who had ousted world No.1 Carlos Alcaraz in the semis - finishing with 28 winners, 10 aces and a perfect eight out of eight net points.
"It was a very, very tough match," Sinner said. "It is great to see Daniil back playing this level."
Sinner also took the chance to congratulate teenage countryman Kimi Antonelli, who won Formula One's Chinese Grand Prix earlier Sunday.
"It hasn't anything to do with tennis, but it has been a special day for Italy," Sinner said. "Because I'm a huge Formula One fan and having a very, very young Italian, Kimi, bringing Italy back home at the top, it's amazing."
In a fast-paced opening set, Medvedev attacked from the outset, putting significant pressure on Sinner. The back-and-forth exchange pushed the 30-year-old to 6-5, only for the Italian to force a tiebreak.
With little to separate them, Sinner proved to be the more clinical player in the tiebreak. He then seized the advantage when Medvedev mishandled a forehand volley at 5-4, and then closed out the set on his second set point.
The second set followed a similar pattern, with the four-time Grand Slam champion Sinner working hard to take the lead, even leaving Medvedev to love in the fifth game to get a 3-2 advantage. However, the Russian didn't give up, levelling after the Italian got a 6-5 advantage to force another tiebreak.
In a bid to reach a decisive third set, Medvedev raced to a commanding 4-0 lead, but Sinner reeled him in, catching him at 4-4 before closing out 7-4 to seal the match.
"I kept believing and kept pushing," Sinner said. "I went for my shots a little more. A third set, we would have started even, so I tried my best to close it out and I am very happy. It was an incredible ending."
