When he was 19 he travelled about giving concerts. He went as far east as Riga. In 1846 he became Court Pianist for King Christian VIII in Copenhagen. He stayed there until 1848, composing four piano concertos as well as concertos for violin, cello, harp and flute. He continued to travel, including to Leipzig where he met Schumann, Mendelssohn and Liszt.
In 1860, Reinecke was made director of the famous Gewandhaus Orchestra concerts in Leipzig, and professor of composition and piano at the Conservatorium. He became director of the Conservatorium and made it one of the best in Europe. He conducted the Gewandhaus Orchestra for 35 years and raised the standard of their playing. He conducted many first performances, including the first complete performance of Brahms's German Requiem (1869).
Perhaps his best-known piece is the flute sonata "Undine". He taught many famous musicians, including Edvard Grieg, Christian Sinding, Leoš Janáček, Isaac Albéniz, Johan Svendsen, Felix Weingartner and Max Bruch.
At the age of 80, Reinecke recorded his playing on piano roll, making him the earliest-born pianist to have his playing recorded in any way.
He retired in 1902, but continued to compose until the end of his life.