He was born at Guebwiller, Alsace. In 1844, he began his musical career, studying singing with Ponchard and composition with Fromental Halévy at the Paris Conservatory. In 1847, he brought out his heroic symphony Roland. In 1853, Weckerlin was most successful in the production of a one-act comic opera, L'organiste dans l'embarras. In 1869, he was appointed assistant librarian to the Conservatory.
In 1863, he produced his comic opera Die dreifach Hochzeit im Bäsethal, and in 1879 Der verhäxt Herbst. These were both in Alsatian dialect. In 1877, he brought out the one-act opera Après Fontenoy. In 1876, he became Félicien David's successor as librarian at the Conservatory and published in 1885 a biographical catalogue. Later he became librarian of the Société des Compositeurs. He gained great renown as a composer of choral works. He married the daughter of the prima donna of Rossini's late Paris operas Madame Laure Cinti-Damoreau.
Weckerlin is best remembered for his piano arrangements of traditional French songs, notably the bergerette, a particular kind of pastoral air, originally for voice accompanied by harpsichord, harp or guitar. His major work, Bergerettes, romances et chansons du XVIII siécle, was published in 1860.
It is record that "He died in Trottberg" but an obituary on his death in 1910 ran:
Death has taken Jean Baptiste Weckerlin, the "dean of French composers, who passed away at Geubweiler, Alsace, where he was born eighty-nine years ago. He was the composer of a successful opera, and has written a number of songs. Weckerlin became librarian at the Conservatory of Paris in succession to Felicien David, and became interested in research work appertaining to the folk-songs of various countries. - Etude
Among his works are:
- oratorio, Le jugement dernier
- cantatas, L'Aurore and Paix, charité, grandeur (1866)
- "ode-symphonie" Les poèmes de la mer, for solo, chorus, and orchestra (1860)
- L'Inde (1873); and La fête d'Alexandre, in the same year.
Writings His Histoire de l'instrumentation depuis le seizième siècle jusqu'à l'époque actuelle won the gold medal of the Académie in 1875.
- Notable recordings of Weckerlin's arrangements were made by the soprano Mady Mesplé for EMI in the 1970s.
- La Laitière de Trianon Joan Rogers, Yann Beuron. Opera Rara 245.
- Gramophone: Vol 59 p704-708 1982 FRENCH PASTORAL SONGS OF THE EIGHTEENTH CENTURY (ed Weckerlin). Mady Mesple (sop); Janine Reisa (hpschd). EMI Pathe Marconi / Conifer 2C 069 14044 (f 5-75). Texts included. Menuet d'Exaudet. Que ne suis-je la fougere. Bergere legere.
- A Dictionary of Opera and Song Themes, Sam Morgenstern & Harry Barlow, Crown Publishers, 1950
- Free scores by Jean-Baptiste Weckerlin at the International Music Score Library Project
- "Weckerlin, Jean Baptiste Théodore". New International Encyclopedia. 1905.
- Jean‐Baptiste Weckerlin (Théodore Jean‐Baptiste Weckerlin) Biography at jrank.org