Sousa was hired as coach in January 2021 but the team — captained by Bayern Munich star Robert Lewandowski — has underperformed under his leadership, finishing last in its group at the European Championship in June.
Poland finished behind England in their qualifying group for next year's World Cup in Qatar and will be in the playoffs in March.
According to reports in the Portuguese and Brazilian media, Sousa has been in talks with the Brazilian club Flamengo.
"Today I was informed by Paulo Sousa that he wants to terminate the contract with the Polish Football Association by mutual agreement because of an offer from another club," Cezary Kulesza, the federation president, wrote on Twitter on Sunday.
"This is extremely irresponsible behavior, inconsistent with the trainer's earlier declarations. Therefore, I firmly refused."