Sixth-seeded Rublev will face world No. 5 Tsitsipas, with both players aiming to win their first ATP Masters 1000 title in the Principality of Monaco.
The relentless Russian player moved past the 22-year-old with a 6-3, 7-5 victory in one hour and 20 minutes.
“It is an amazing feeling. It is my first [ATP Masters 1000] final, so I am really happy,” he said.
The world number eight came out solid, hitting 21 winners while converting five of five break points faced.
Overall, he made 19 unforced errors comparing to the 26 produced by the unseeded player.
In their first-ever encounter, the Moscow native grabbed the opener 6-3 in 32 minutes.
In the second set, Ruud suffered an early break, though regrouped quickly, making good use of his powerful forehand to level the contest at 2-2, taking the lead at 3-2, and spanning his advantage to 4-2.
Then, Rublev made a comeback from a break down, sealing the set, 7-5 to win the match.
Speaking about his opponent, he stated: “Casper is a really amazing player, especially on clay.”
Adding: “He started [by going] up with the break, and I felt like I needed to raise my level, raise my speed [and] hit harder. Otherwise, I had no chance. I started to do it, and then I started to play better, and he started to miss a bit more. I think that was the key.”
On Sunday, the 23-year-old will meet Stefanos Tsitsipas, seeking his ninth ATP title and maiden Masters 1000 crown at the Monte-Carlo Country Club.
The Greek player claimed the win over Britain’s Daniel Evans in straight sets 6-2, 6-1 to make his first Monte Carlo final appearance.
In a post-match interview, Tsitsipas commented: “It was really difficult to maintain my level of consistency, and I am really happy I managed to deal with all the different moments during the match. I had a lot of opportunities to hit the forehand and think how I wanted to construct the point.”
It will be Tsitsipas third ATP Masters 1000 final; in 2018, he lost to Nadal in Toronto at the Canadian Open.
In 2019, world number 1 Novak Djokovic outlasted the Athens native at the Madrid Mutua Open.
On his way to the final, the fourth seed overcame 2021 Dubai champion Aslan Karatsev, Santiago Open Champion Cristian Garin, Alejandro Davidovich Fokina, and Evans without dropped a set on the clay-court tournament.
The new Rolex Monte-Carlo Masters 1000 champion will be crowned on Sunday.