In a letter read out during a ceremony at the terminal in Świnoujście, President Andrzej Duda said: "I trust that this heralds further successful ventures and new, spectacular economic successes for Poland."
Poland has been making determined efforts to strengthen its energy security, diversify its sources and wean itself off Russian gas.
Jerzy Kwieciński, CEO of Polish state-owned oil and gas company PGNiG, hailed the 100th delivery of liquefied natural gas to the terminal in Świnoujście, supplied by the Qatargas company, as a "symbolic and historic moment."
He added: "Every month three or four such tankers arrive in Poland. At first they were tankers from Qatar. At the moment we have more and more deliveries from the United States.”
The first commercial delivery to Świnoujście took place in June 2016.
The LNG terminal is to be expanded under a set of deals signed last month and worth PLN 1.9 billion (EUR 427m, USD 482m).
The Polish government’s pointman on strategic energy infrastructure, Piotr Naimski, said last year that Poland would stop buying Russian gas after its long-term supply contract with Russia’s state-owned producer Gazprom expires in 2022.