Born in Sosnowiec, Poland, Polanski moved to Germany as an infant, joining Borussia Mönchengladbach's youth ranks at the age of eight.

[4] During his first and only season, as the Madrid side finished just one place above the relegation zone, he was first choice, often partnering Javier Casquero in central midfield.

[8] On 25 January 2013, Polanski joined fellow top division team TSG 1899 Hoffenheim, penning a deal until June 2015.

[10] He was a key member of the under-21s at the 2006 UEFA European Championship, scoring a magnificent long-range goal in the fixture against Serbia and Montenegro;[11] his form made AS Monaco FC enquire about his services, but Mönchengladbach promptly rejected the offer.

On 26 July, he was called up by manager Franciszek Smuda for a friendly with Georgia, making his debut in the game which took place on 10 August.