Peko signed with the Denver Broncos as an undrafted free agent following the 2016 NFL draft.

On May 3, 2016, Peko signed with the Denver Broncos as an undrafted free agent following the 2016 NFL draft.

[6] During the 2017 season, Peko was involved in multiple transactions; he was signed and released five times.

[20] On November 4, 2019, Peko was claimed off waivers by the Indianapolis Colts, but was waived five days later and re-signed to the practice squad.

He also put up the only forced fumble in his career in the first of those last two games, a 34–3 win against the Miami Dolphins.

[41] In Week 13 against the Indianapolis Colts, Peko put on a season-best performance with 2 QB hits and 1 pass defensed against quarterback Gardner Minshew; the Titans lost 31–28 in overtime.

On October 13, 2024, against the Dallas Cowboys in Week 6, Peko suffered a torn pectoral muscle that resulted in him being placed on injured reserve after undergoing season–ending surgery.

In 2019, Peko's wife, Giuliana, was diagnosed with cancer, specifically stage 3 Hodgkin's lymphoma, and Kyle was excused for the first day of Bills' training camp.