Bencic improved to 18-3 this year.
As has been the case all tournament long, Andreescu showed no signs of wilting when the big moments came her way.
The 18-year-old upset the sixth seed 6-3 2-6 6-4 to become the first wildcard to reach the final at Indian Wells. Little known at the time, Osaka used her Indian Wells victory as a launching pad to beating Serena Williams for the U.S. Open title and winning the Australian Open while becoming the world's top-ranked player.
"This past week, it's been a dream come true playing in front of these unbelievable crowds", Andreescu said in a courtside interview after putting her name alongside Serena Williams who reached and won the 1999 final at 17.
Andreescu will earn $1.354 million USA if she wins the final and $686,000 if she loses.
Andreescu missed a match-point opportunity on Svitolina's serve, but then won the next game to finish it in dramatic fashion, fighting off three break points. Either total is well above her current career earnings of $350,909.
Raonic is 2-0 in his career against Thiem, winning both matches in straight sets on hard-courts in 2016. Kerber has won seven of her last nine matches on outdoor hard court.
Elina Svitolina was a tougher challenge in Saturday's semi-final but Andreescu's determination, hunger and aggression got her past the world number six. The Canadian had 57 unforced errors, though, while Svitolina made 29.
Svitolina, the 2017 Toronto Rogers Cup champion, responded with a break to tie the third set at 3-3. "I'm definitely playing how I feel it, and it's going well so I'm not planning on changing that". A couple of shaky serves from Svitolina opened the door for Andreescu to retake her advantage and the Canadian needed no second invitation as she sealed the break with rocket of a forehand down the sideline to make it 4-3. Kerber has won the last three meetings against Bencic, and all six matches overall have been decided in six straight sets.