Swiatek, 19, capped a stunning fortnight at Roland Garros with a 6-4 6-1 win over Australian Open champion Sofia Kenin in the Paris final on Sunday (AEST).
The unseeded player did not drop a set over her seven rounds, other notable wins including an emphatic victory over tournament favourite Simona Halep in the fourth round and seeing off the 2019 finalist, Marketa Vondrousova, in her first match.
Just two years ago she had won the junior title at Wimbledon and prior to this tournament had never reached the last eight of a tennis Major.
Her run to victory captured the attention of Lewandowski, another of Poland's sporting success stories.
"What an amazing success, what a great story! Good job Iga Swiatek," Lewandowski wrote on Twitter after the win over Kenin, having also sent a message of support earlier this week.
What an amazing success, what a great story! Good job @iga_swiatek 🎾👏🤜🤛— Robert Lewandowski (@lewy_official) October 10, 2020
Swiatek had earlier referenced the traction her run at the event had been getting in her country.
"I want to thank all the fans and everyone watching in Poland; I know it's pretty crazy back home," she said in her on-court interview.
Swiatek was later asked in her news conference if she understood her life was about to change.
She added: "That's true. I mean, it's hard to comment on that right now because I need to come back home first, see what's going on in Poland.
"I know it's going to be crazy. I think I'm going to get used to that, it's not going to be a problem for me. I didn't have a problem with getting attention, with people surrounding me.
"I think it's going to be okay for me. I really appreciate all the support I got during the whole two weeks.
"Even though I wasn't on my phone and I wasn't answering every person, I know that the whole country was behind me and they all believed in me. I'm going to be happy and proud."
Poland captain Lewandowski, who was recently named UEFA Player of the Year, will be hoping to cap a fine sporting weekend for the nation when his team hosts Italy in the UEFA Nations League on Monday (AEST).