World number one Alcaraz was defeated 2–0 in sets, ending the Spaniard's run of two straight titles and a 16-match unbeaten streak in 2026.
"He's a fantastic player with fantastic strokes, defense, attack, serve, return, everything. So you have to be at your best – and I was," Medvedev said after the victory.
In the final, Medvedev will face world number two Jannik Sinner. Indian Wells is, after the four Grand Slam tournaments, one of the most prestigious on the ATP Tour.
The final starts at 10:00 PM local time in Sweden on Sunday evening.
