Despite speculation that he would declare for the 2020 NFL draft, and being listed as the number 2 draft-eligible cornerback by Mel Kiper, Adebo announced that he would return to Stanford for his senior year.

[12] Throughout training camp, Adebo competed to be a starting cornerback after the retirement of Janoris Jenkins left a role vacant.

The Saints would sign Prince Amukamara and hold an open competition that also included veterans Brian Poole, Grant Haley, P. J. Williams, and Ken Crawley.

On September 12, 2021, Adebo started in his professional regular season debut and recorded three combined tackles (two solo), a pass deflection, and had his first career interception off a pass thrown by Aaron Rodgers intended for wide receiver Davante Adams to return it for 33-yards as the Saints routed the Green Bay Packers 38–3 in their home-opener.

In the Saints' week 7 game against the Denver Broncos, Adebo suffered a broken femur and was ruled out for the remainder of the season after undergoing surgery.