Haddad Maia, who had never advanced past a Grand Slam second round, became the first Brazilian woman in 55 years to reach a major semi-final after beating world number seven Ons Jabeur in the quarter-finals.
After failing to extend her remarkable week to reach the final, Haddad Maia left Roland Garros with a smile.
"Our first goal was to go to the third round," the world number 14 said.
"We worked very hard, and me and my team deserve and need to be very proud of ourselves, because it's not easy to be in this stage.
"I think this match and this week will bring me a lot of things to improve, things that we learn to build our game, our mentality."
The Brazilian's distinctive resilience was not enough against world number one Swiatek, who is bidding for her third French Open title.
After a first set dominated by the Pole, Haddad Maia fought back, forcing a tiebreak in the second set, but wasting the chance to send the match to a decider.
"I was a little bit more emotional in the beginning," Haddad Maia said.
"Playing for the first time semi-finals against the number one in the world, with a lot of Brazilians there, I couldn't be very disciplined and concentrated in the things that I had to be, but I did my best."
