Penn, best known for his role as Kumar in the Harold & Kumar film series, beat actress Cheryl Hines with his made-from-scratch fish tacos on the final episode of the cook-off aired on Monday.

He donated his prize money to the UN's agency for Palestinian refugees, UNRWA USA.

"I chose the United Nations agency for relief and works for Palestinian refugees; $25,000 can feed over a thousand people for a year," Penn told celebrity chef Gordon Ramsay on the show.

Before his big win, Penn had tweeted: "Hope I win [MasterChef]! $32 can provide a blanket, mattress, & winter jacket to refugees in Syria."

UNRWA thanked the actor helping shed light on the hardships that millions of Palestinian refugees face.

"We can't thank you enough for your generosity and for highlighting the plight of Palestine refugees," the UN agency said on Facebook.

It added that Penn would send postcards to people who donate to the agency and send him an image of their tax receipts on Twitter.

UNRWA was created in 1949, the agency was established to provide direct relief for the 652,000 Palestinians that fled or were expelled from their homes when the state of Israel was created.

A failure to resolve the refugee issue has led to repeated extensions of UNRWA's mandate.

The agency now supports five million Palestinians who were made refugees by the 1948 and 1967 wars and their descendants living in Jordan, Lebanon, Syria, the occupied West Bank and the Gaza Strip.

It provides education, healthcare and social services and is predominantly funded by voluntary contributions, mainly from donor states.