This is a list of winners and nominations for the Tony Award for Best Costume Design in a Musical for outstanding costume design of a musical. The award was first presented in 1961 after the category of Best Costume Design was divided into Costume Design in a Play and Costume Design in a Musical with each genre receiving its own award. That lasted for only one year, but the Costume Design category was split in two again in 2005 and has remained that way since.
In 2010, Santo Loquasto received a nomination for Best Costume Design for a Musical for Ragtime. Loquasto, who was previously nominated for the same show in the same category in 1998, was later disqualified because the designs were predominantly recycled work from the earlier production. No replacement was made for the nomination.
Award wins includes the former Best Costume Design category and the nominations includes only the specific category.