The Czech team says Baros announced his decision to quit after the Czechs were eliminated from the European Championship following a 1-0 loss to Portugal in the quarterfinals on Thursday.
The 30-year-old has been the second best Czech scorer of all time with 41 goals in 93 international games.
The best scorer at the 2004 Euro who also won the Champions League with Liverpool has been struggling in the national team in recent years and netted just once in the Euro 2012 qualifying campaign.
He didn't score at the tournament and was repeatedly booed by fans.
Baros plays for Galatasaray.