The world No.106 reached her first career final by beating two-time Major champion Azarenka 6-4 6-2, having impressively seen off Madison Keys in the last eight.
It took just 66 minutes for Samsonova to win as she put on a powerful display of hitting, firing down 11 aces.
The 22-year-old did not lose serve in the match and is the first qualifier to reach a WTA 500 final this season.
"It's all incredible for me, it's so new, and I'm very happy for it," Samsonova said amid a week that will deliver her a rankings surge.
"It’s unbelievable for me. It is the most important [week] of my life up to this moment.
"I'm sure it’s going to be a tough match because [Bencic] plays very good on this surface, and she's a good player. I will try to do my best and focus on my game, and we will see."
No.5 seed Bencic battled to a 7-5 6-4 victory over Alize Cornet in her last-four clash and will go into the final as favourite.
While the win came in straight sets, it was a hard-fought encounter, with Bencic winning all four of her break points while Cornet forced 10 but only converted two, which proved to be the difference.
Bencic, who will be encouraged ahead of Wimbledon, has now made four grass-court finals in her career and will seek her first WTA Tour title since October 2019.
The Swiss star, who had 29 winners and just 19 unforced errors against Cornet, lost to Iga Swiatek in Adelaide earlier this year in her only final appearance since that title.
"I always try to play as many tournaments on grass as possible because I just love the surface," Bencic said.
"Of course it gives me a lot of confidence. It's always great to have this confirmation on grass that it is working well."