Signature Theatre announced Thursday that it will honor Lansbury at a gala celebration in April.
Lansbury is a five-time Tony Award-winning Broadway musical star. Two of her Tonys are for Sondheim musicals - the 1974 revival of "Gypsy" and "Sweeney Todd" in 1979.
Lansbury's first musical theater appearance was in "Anyone Can Whistle." Sondheim wrote the score, but the show only ran for nine performances. Sondheim says the award will help make it up to Lansbury.
Lansbury returns to Broadway this month in Sondheim's "A Little Night Music" with Catherine Zeta-Jones.