After his four-year college career was completed after his senior season in 2014–15, Pietila, who was the captain, was signed to a two-year entry-level contract with the New Jersey Devils on May 27, 2015.

[4] In his debut professional season in 2015–16, Pietila was initially reassigned to AHL affiliate, the Albany Devils.

He recorded his first NHL goal on March 31, 2016, against the Florida Panthers with only 5.1 seconds remaining in a 3-2 loss.

[5] On July 26, 2017, the Devils re-signed Pietila to a two-year, two-way contract worth $1.335 million and $667,000 annually.

As a free agent from the Ducks leading into the pandemic delayed 2020–21 season, Pietila belatedly signed a professional tryout contract with the Hershey Bears of the AHL, affiliate to the Washington Capitals, on February 8, 2021.