Lea began her career as a child actress on Broadway, appearing in productions of Les Misérables (1995–1996), Ragtime (1997–1999), Fiddler on the Roof (2004–2005), and Spring Awakening (2006–2008). Michele came to prominence playing Rachel Berry on the Fox series "Glee" (2009–2015), for which she received nominations for an Emmy Award, two Golden Globe and three Grammy Award nominations for music recorded for the series, also spawning multiple hits on the Billboard charts. Michele subsequently starred as Hester Ulrich on the Fox series "Scream Queens" (2015–2016) and as Valentina Barella on the ABC sitcom "The Mayor" (2017).
In 2022, Michele returned to Broadway starring as Fanny Brice in the musical revival of Funny Girl, where she received widespread critical acclaim for her performance.