[5] On March 20, 2018, Nnadi participated at Florida State's pro day and chose to perform the short shuttle (4.97s) and vertical jump (25.5").

At the conclusion of the pre-draft process, Nnadi was projected to be a third or fourth round pick by NFL draft experts and scouts.

[6][7] The Kansas City Chiefs selected Nnadi in the third round with the 75th overall pick in the 2018 NFL draft.

[12] In Week 11 of the 2019 season against the Los Angeles Chargers on Monday Night Football, Nnadi recorded his first career interception off Philip Rivers in the 24–17 win.

[23] Nnadi has celebrated each Chiefs win during the 2019 season by paying the adoption fee for a dog at a local Kansas City shelter.