Muchova, who beat world number two Aryna Sabalenka in the semi-finals, looked out for the count after Swiatek raced through the first set and went 3-0 up in the second.
But Muchova fought back, cutting down on unforced errors and troubling the Pole with her one-handed sliced backhand and drop shots to force a decider.
Despite leading in the third, Muchova could not complete what would have been a memorable recovery and ended up watching as Swiatek lifted her third French Open trophy in four years.
"I felt I was very, very close. Close match. To call myself a Grand Slam finalist is an amazing achievement and, for sure, big motivation for me to work in the future and get a chance again to play for these big titles," she said.
Plagued by injuries throughout her career, including when she played in the juniors, Muchova, a 2021 Australian Open semi-finalist, dropped to the mid-200s after another injury in 2021.
She said this week that some doctors had told her after that 2021 injury that she might not play again. However, she battled back into the top 50 once more going into the French Open.
"It's a very big motivation, now that I know that Iga is world number one and I was so close. I think now that I can do it," she said. "It's good for the confidence. It says to me that I'm able to do this, to do these big results.
"It's very motivational and now I feel I can do it and I will for sure try to get there again and to put up a fight for the title on the next stages."
Muchova, whose defeat was her first against a top three player in her career after five wins, said she was now looking forward to next month's Wimbledon tournament and the grass season where she feels more comfortable.
"I wouldn't expect it that much on the clay, honestly. I look forward to playing on the grass, on the fast surfaces, that's for sure the surfaces I prefer and I like more," she said. "The main focus is obviously Wimbledon."
