The victory was her 12th win in a row.
The 22-year-old Swiss, whose career was disrupted by a string of back and wrist injuries, had beaten six top-10 players in her winning streak, including world number one and defending Indian Wells champion Naomi Osaka in the fourth round here.
Bencic next plays the victor of Thursday's match between No 8 seed Angelique Kerber and Venus Williams.
However, the three-time grand slam victor silenced her critics with a 2018 win over Serena Williams at Wimbledon, adding to her slam haul, and demonstrating that she was very much still a contender.
When asked where a title this week would rank in his career, Raonic said, "It would be there, I believe, parallel to the Wimbledon final (in 2016), if not higher, just because it's going through a week amongst the best players in the world without sort of ending with a loss".
She's the first wild card to reach the women's final at Indian Wells. "And I think this year all the wins have definitely given me confidence".
At the break, Andreescu told her coach, Sylvain Bruneau, "My feet were burning" and that she was having trouble moving.
"She played really tricky", Kerber said after the match.
Close games marked the start of the third, with Pliskova fighting off four break points in a game that went to eight deuces to hold for 2-2. And the world No60 showed few early signs of nerves against Kerber, whom she broke in the opening game of the match before serving out to take the first set.
"Ever since I was little, I was always changing the pace", Andreescu said.
"If someone told me at the beginning of the year that I would be top-50 during Indian Wells, I would have told them that they're insane", she said. I know this. I was expecting a tough match.
Bencic could have made life easier for herself against Pliskova but only managed to convert four of her 16 break points against the Czech's serve.
Then the German again held serve to win a third straight game for commanding 4-1 lead. Kerber secured the break when Andreescu's attempted drop shot went into the net to pull to within 5-4 as the Canadian received some treatment on her right leg at the break. "Another goal of mine was to make history, and I just did". I actually never feel like I'm getting tired-or more exhausted than my opponent on the court. "I just want to enjoy this moment, because I don't want to take anything for granted".