He is best known for his work on Broadway, including originating the roles of Nick Healy in Jagged Little Pill (2019–2021), Dmitry in Anastasia (2017–2018), and Michael in The Bridges of Madison County (2014).

His breakthrough was in the original Off-Broadway production of Pasek & Paul's stage adaptation of Dogfight,[4] and he played Fiyero in the 10th anniversary company of Wicked on Broadway.

He has made appearances on several television series such as Unbreakable Kimmy Schmidt, The Code, and Pretty Little Liars: Original Sin.

In 2020, Klena was nominated for a Tony Award for Best Featured Actor in a Musical for his portrayal of Nick Healy in Jagged Little Pill.

[6] He grew up with his two younger siblings in West Covina, California, outside of Los Angeles, where he attended South Hills High School.

[8] Klena attended the University of California, Los Angeles where he initially studied theater but switched his major to psychology.

[11] Subsequently, he played son Michael Johnson in the original Broadway musical The Bridges of Madison County.

[5] The show went on hiatus in March 2020 and reopened in October 2021 but closed a few months later due to the Omicron surge in New York City.