He played college football at the University of Miami and was selected by the Pittsburgh Steelers in the sixth round of the 2015 NFL draft.

[6] Chickillo was invited to the NFL Scouting Combine and was able to participate in the full workout and complete all the positional drills.

Chickillo finished his rookie season with a total of six combined tackles and a forced fumble, while appearing in seven regular-season contests and two postseason games.

[14] Although he was mainly featured on special teams, he began to receive more reps as a rotational outside linebacker after Dupree missed the first ten games due to an abdominal injury.

On October 9, 2016, Chickillo recorded three solo tackles, a forced fumble, and his first career sack on New York Jets' quarterback Ryan Fitzpatrick, during the Steelers' 31–13 victory.

During a Week 9 13–21 loss to the Baltimore Ravens, Chickillo made a season-high six combined tackles and was credited with a half a sack on Joe Flacco.

The next game, he made a total of four tackles, forced a fumble, and sacked Dak Prescott during a 30–35 loss to the Dallas Cowboys.

[10][15] He returned as the Steelers' third left outside linebacker behind Dupree and Moats, but began the regular season featured on special teams.

In addition, Tyler Matakevich blocked a punt, which Chickillo recovered in the end zone for his first career touchdown and gave the Steelers their first points of the season.

[16] On March 13, 2018, the Steelers extended an original round tender offer to Chickillo as a restricted free agent.