Lachner was born in Rain am Lech to a musical family (his brothers Ignaz, Theodor and Vinzenz also became musicians). He studied music with Simon Sechter and Maximilian, the Abbé Stadler. He conducted at the Theater am Kärntnertor in Vienna. In 1834, he became Kapellmeister at Mannheim. In 1835 he received the first prize for symphonic composition at Vienna with his Sinfonia passionata, and became royal Kapellmeister at Munich, becoming a major figure in its musical life, conducting at the opera and various concerts and festivals. His career there came to a sudden end in 1864 after Richard Wagner's disciple Hans von Bülow took over Lachner's duties. Lachner remained officially in his post on extended leave for a few years until his contract expired.
Lachner was a well-known and prolific composer in his day, though he is not now considered a major composer. His work, influenced by Ludwig van Beethoven and his friend Franz Schubert, is regarded as competent and craftsman-like, but is now generally little known. Among his greatest successes were his opera Catharina Cornaro (1841, preceding Donizetti's own opera by three years), his Requiem, and his seventh orchestral suite (1881).
In the present day it may be his organsonatas (Opp. 175, 176, 177) and chamber music, in particular his music for wind instruments, that receive the most attention, though his string quartets and some of his eight symphonies have been performed and recorded. His songs, some of which are set to the same texts that Schubert used, contributed to the development of the German Lied.
For performances of Luigi Cherubini's Médée in Frankfurt in 1855, Lachner composed recitatives to replace the original spoken dialogue, and it was this version, translated into Italian, which was used in many twentieth-century revivals and recordings of that opera.