Sweden's outgoing Prime Minister Ulf Kristersson announced the deployment on Tuesday, citing the threat from Russia.
Speaking at a specially convened news conference, he said the Swedish forces' task would be to protect the NATO logistics hub in Poland and help ensure the transport of important equipment to Ukraine.
The operation is due to begin on 1 December and run until June 2027.
The Rzeszów hub, in south-eastern Poland, handles a large share of Western support for Ukraine.
Dutch Patriot systems are currently stationed there, and Swedish ones will replace them from December.
About 100 Swedish troops will be sent, according to public broadcaster SVT.
Poland's Defence Minister Władysław Kosiniak-Kamysz confirmed the plan to the Polish news agency PAP.
He thanked Sweden's military and government, including Defence Minister Pål Jonson, who he said had been personally involved.
He described the Swedes as "wonderful, proven allies" who, since joining NATO in 2024, have played a key role in the alliance.
Jonson said Sweden must prepare "for a longer-term worsening of the security situation."
Swedish media noted that the government announced the deployment after Polish Prime Minister Donald Tusk warned of possible Russian attacks.
Kristersson also pointed to recent incidents in Europe and to drone strikes on ships in the Black Sea.
SVT described the mission as Sweden's most complex military operation within NATO.
The deployment follows other Swedish support for the alliance's eastern flank.
The country's Gripen fighter jets have been on air defence duty over Poland since early October, after Kristersson announced the move at the end of September in response to airspace violations.
(ał)
Source: PAP, IAR