Kalinowski was born in Wyszków. He was first elected to the Sejm in 1993, and was reelected in the subsequent elections of 1997, 2001, 2005 and 2007. At the 2005 legislative elections of 25 September, he gained 15,855 votes in the 18th electoral (Siedlce) district. He was reelected to the Sejm once again at the legislative elections of 21 October 2007.
Kalinowski was deputy Prime Minister and Minister for Agriculture from April to October 1997, in the cabinet of Wlodzimierz Cimoszewicz. He was returned to both these positions again from October 2001 to March 2003, in the cabinet of Leszek Miller. Kalinowski succeeded Waldemar Pawlak as the leader of the PSL party in November 1997 and he held this position to March 2004. He contested the Polish presidential election as the PSL candidate in 2000 (5.95% of votes), and again in the following presidential elections of 2005 (1.8% of votes). Following the 2005 Polish legislative elections, he was elected to the position of Vice-Marshal of the Sejm of the Republic of Poland (deputy Speaker of the lower house) in November. He was reelected to this position following the legislative elections of 2007.
On 7 June 2009 Kalinowski was elected Member of European Parliament from Masovian Voivodeship constituency, gaining 51,014 of the votes.