This is a list of music-related events in 1820.

• Pietro Raimondi returns to Naples and begins his career as an opera composer.
• The Musical Fund Society is founded at Musical Fund Hall in Philadelphia. Its first public concert on April 22, 1821, featured Beethoven's 2nd Symphony.
• Franz Liszt plays in public for the first time in Ödenburg.

• Ludwig van Beethoven – Piano Sonata No. 30
• Franz Berwald – Violin Concerto in C sharp minor, Op. 2
• Fanny Mendelssohn-Hensel – "Annette", H-U 14
• Friedrich Kuhlau
  • 3 Sonatinas, Op.20
  • Fantasy and Variations, Op.25
• Felix Mendelssohn
  • "Raste Krieger, Krieg ist aus" MWV K 2
  • Violin Sonata in F major, MWV Q 7
  • Recitativo in E minor, MWV U 11
  • Piano Piece in E minor, MWV U 12
  • Piano Piece in E minor, MWV U 18
• Ignaz Moscheles – Piano Concerto No.3, Op.58
• Ferdinand Ries – Sextet, Op.100 (On "The Last Rose of Summer")
• Friedrich Schneider – Das Weltgericht, Op.46
• Franz Schubert
  • Lazarus, oratorio
  • Quartettsatz, D. 703
  • Psalm 23, D.706
• Louis Spohr
  • Grand Rondo in G major for violin and piano, Op. 51
  • Potpourri on Irish Themes in A major, Op. 59
  • Potpourri on Themes from Mozart's Die Zauberflöte for violin and piano in F-sharp minor, Op. 50
  • Quintet for piano and winds in C minor, Op. 52
  • Symphony No. 2 in D minor, Op. 49
  • Violin Concerto No. 9 in D minor, Op. 55

• Juan Crisóstomo Arriaga – Los Esclavos Felices
• Friedrich Kuhlau – Elisa, Op.29 (premiered April 17)
• Giovanni Pacini – La schiava di Bagdad (première October 28 at Teatro Carignano, Turin)
• Gioacchino Rossini – Maometto II (premiered Dec. 3 in Naples)
• Franz Schubert – Sakuntala, D. 701 (started, never finished)

• "Hail to the Chief" – words, Sir Walter Scott; music James Sanderson
• "D'ye Ken John Peel" – words, John Woodcock Graves. music traditional.

• January 9 – Pavel Křížkovský, conductor and composer (d. 1885)
• February 10 – Cornelius Gurlitt, composer (d. 1901)
• February 17 – Henri Vieuxtemps, violinist and composer (d. 1881)^[1]
• March 7 – Gustav Graben-Hoffmann, German composer and voice teacher (d. 1900)^[2]
• March 24 – Fanny Crosby, American lyricist (d. 1915)
• May 21 – Michel Lentz, lyricist of the Luxembourg national anthem (d. 1893)
• June 22 – Franz Kroll, pianist (died 1877)
• July 7 – George Cooper, organist (died 1876)
• July 20 – Enrico Crivelli, Italian opera singer (d. 1870)
• July 26 – Maria Severa Onofriana, Portuguese singer and guitarist, considered the founder of fado (d. 1846)^[3]
• August 13 – George Grove, music writer (d. 1900)
• August 30 – George Frederick Root, songwriter (d. 1895)
• September 5 – Louis Köhler, pianist, composer and conductor (d. 1886)
• October 6 – Jenny Lind, Swedish singer (d. 1887)^[4]
• December 17 – Karl Anton Eckert, conductor and composer (d. 1879)
• date unknown
  • Maria Severa Onofriana, fado singer (d. 1846)
  • Anna-Kajsa Norman, Swedish folk musician (d. 1903)

• February 2 – Peder Schall, composer (b. 1762)
• March 26 – Jean-Étienne Despréaux, French dancer, choreographer and composer (b. 1748)
• August 6 – Antonín Vranický, Bohemian violinist and composer (b. 1761)^[5]
• August 28 – Antonín Kraft, cellist and composer (b. 1749)
• October 3 – Ludwig Wenzel Lachnith, horn player and composer (b. 1746)
• date unknown – Marie Bigot, piano teacher (b. 1786)
• probable
  • Mikhail Matinsky, scientist, writer and composer (b. 1750)
  • Louis Joseph Saint-Amans, composer (b. 1749)