While still in school, Costello made his professional debut as Rodolfo in
La bohème with the
Fort Worth Opera in March 2006, and his European debut with
Opéra National de Bordeaux as Nemorino in ''
L'elisir d'amore in September 2006. Also in 2006, he made debuts with the Dallas Opera as Leicester in Maria Stuarda and with Opera Orchestra of New York as the Fisherman in Guillaume Tell'' (his
Carnegie Hall debut). Costello made his debut at the
Metropolitan Opera on the opening night of its 2007-2008 season, as Arturo in
Lucia di Lammermoor He portrayed Cassio in Verdi's
Otello at the
Salzburg Festival in 2008. He made his debut at
Covent Garden in 2009 as Carlo in
Linda di Chamounix. That same season, he debuted at
Lyric Opera of Chicago as Camille in
The Merry Widow and at the Tchaikovsky Concert Hall in
Moscow as Roméo in
Roméo et Juliette, the role of his subsequent
San Diego Opera debut. Other notable roles include Christian in
Cyrano
with
Opera Company of Philadelphia, the title role of
Roberto Devereux at The
Dallas Opera and Rinuccio in
Gianni Schicchi at the
Spoleto Festival conducted by
James Conlon. On April 30, 2010, Costello originated the role of Greenhorn (Ishmael) in the world premiere of
Jake Heggie's
Moby-Dick at The
Dallas Opera (with
Ben Heppner as Captain Ahab). In 2010, he also appeared as Rodolfo in
La bohème at
Deutsche Oper Berlin,
Cincinnati Opera, and
Wiener Staatsoper, and debuted at the
Salzburg Festival in
Roméo et Juliette. In November 2010, he portrayed
Percy in
Anna Bolena, and thereby portrayed the 3 lead tenor characters in each of
Donizetti's Tudor Operas within a 4-season span at the Dallas Opera. His debut at the
Santa Fe Opera was as Roméo in
Roméo et Juliette in July 2016. ==Honors==