The pro-Israel march proceeded from the Royal Castle Square to the Charles de Gaulle Roundabout in downtown Warsaw, Polish state news agency PAP reported.
The rally was called A March for the Release of Hostages, A March Against Anti-Semitism.
Participants carried flags of Israel and Poland, as well as banners reading "Israel, You're Not Alone," "Stop Hamas Terror - Free the Hostages" and "Gaza Free From Hamas."
Israel's ambassador to Poland, Yacov Livne, thanked everyone for attending the rally and said it was "the biggest pro-Israeli march held so far in Warsaw."
The event concluded with a minute's silence in memory of those killed in the ongoing Israel-Hamas war.
On Saturday, protesters gathered outside Israel's embassy in Warsaw to demand an end to the bombing of the Gaza Strip by the Israeli army, the PAP news agency reported.
The rally was entitled No More Bombs - Free Palestine.
Participants chanted "Gaza, Warsaw - a Common Cause," among other slogans.
The war between Israel and Hamas broke out when the Palestinian Islamist group launched attacks from the Gaza Strip on October 7, killing 1,400 people and kidnapping more than 200 as hostages, according to the Israeli government.
Israel has since been bombing Gaza, as well as mounting a ground assault on the territory, killing 13,000 people, including more than 4,500 children, according to Gaza's Hamas-run health ministry.
On Sunday, there were growing hopes of a deal to release some of the Israeli hostages being held by Hamas, the British broadcaster BBC reported.
Michael Herzog, Israel's ambassador to the United States, said he was hopeful that a "significant number" could be released "in the coming days."
Source: PAP, Reuters, BBC
Click on the audio player above for a report by Radio Poland's Michał Owczarek.