The 2011 pole sitter will join Fisher's full-time IndyCar driver, Josef Newgarden, in a two-car lineup announced Thursday.
Tagliani will drive the No. 68 Honda.
Tagliani was the 2009 Indy 500 top rookie with an 11th-place finish. Two years later, he became the only Canadian driver to win the pole.
Tagliani has five career starts in the 500. His best finish was 10th in 2010. He has started in the first two rows twice, on the pole in 2011 and fifth in 2010, and has led 23 total laps.