The 42nd-ranked Finn had gone out at the first hurdle at Munich and Rome after making a solid quarter-final showing to start his pre-French Open campaign, where he lost to eventual champion Novak Djokovic.
Both times, he lost to on-form Latvian Eernests Gulbis, who went onto challenge Rafael Nadal in three sets last week in Rome.
Nieminen sees the defeats - his only two in the first round this season - as a mere blip. He is relying more on the quarter-final showing he produced in Monte Carlo, where he beat Juan Del Potro and Milos Raonic before going out to eventual champion Novak Djokovic.
"I have a lot of confidence from Monte Carlo," said the Finn with two career titles. "The courts and the clay there are similar to Paris and I felt I played well.
"I haven't done well at a Grand Slam - a 2008 quarter-final in Australia was his last solid result - and I'd love to carry this confidence and game to Paris."
Nieminen is playing for the first time at the tree-shaded Rochusclub venue which formerly hosted the World Team Cup for more than three decades.
The Finn took 76 minutes to get past Slovak Lacko, whom he beat in the Helsinki Challenger last November, with the winner breaking five times.
"Today I played well in the heavy conditions. I don't think they were the favourite of my opponent. You can't expect to get any quick points, you have to work and build on every one."
The final tune-up event prior to the Sunday start at Roland Garros features Serb Janko Tipsarevic in the top seeding position, ahead of Munich winner Tommy Haas, still a wildly a popular figure in his homeland despite living in Los Angeles.
Juan Monaco takes the third seeding, with Argentine Juan Monaco fourth.
Nieminen improved his record this season to 19 wins, 12 defeats.
Lacko, ranked 74th, was playing in his first ATP-level match since a first-round loss in Miami two months ago to Ivan Dodig, a first-round Dusseldorf victim.
In other results, Brazilian qualifier Andre Ghem, a 30-year-old ranked 260th, won the third ATP match of his career as he stopped Japan's Go Soeda 6-4, 6-0.
Results from the second day of the Dusseldorf Cup ATP tournament (x denotes seed):
Andr Ghem (BRA) bt Go Soeda (JPN) 6-4, 6-0
Jarkko Nieminen (FIN x6) bt Luks Lacko (SVK) 6-3, 6-1