Batmanglij majored in music at Columbia University where Vampire Weekend formed in 2006. "At Columbia, I would study classical harmony in classes and I would study music on my own, and I would try to re-create songs that I love in recordings...that was really how I learned." The name of the group comes from the movie of the same name that bandmate Ezra Koenig and his friends made over summer vacations. Batmanglij produced their self-titled debut album shortly after graduation while concurrently working multiple full-time jobs. He also produced the band's follow up album, Contra, which sold 124,000 copies in its first week and landed atop the Billboard 200 charts. Batmanglij plays guitar, keyboard and sings in the band but also acts as a lyricist and songwriter, co-writing the song "Diplomat's Son" on Contra. Koenig has described himself and Batmanglij as "the two main songwriters in the band."
On March 18, 2013, Vampire Weekend released two songs from their album Modern Vampires of the City, "Diane Young" and "Step". Within two weeks each song had garnered more than 1 million views on YouTube. Music for both songs is credited to Batmanglij and Koenig, and lyrics are credited to Koenig. Modern Vampires of the City is the first Vampire Weekend album Batmanglij did not produce alone; for this record he collaborated with longtime friend Ariel Rechtshaid and the two co-produced the album together. It was released May 14, 2013.
On January 26, 2016, Batmanglij announced on Twitter that he had left Vampire Weekend to pursue solo projects, but that he would continue to collaborate with Koenig on future projects and Vampire Weekend songs.