Njoku is one of nine children born to Nigerian parents of Igbo heritage[1] who immigrated to the United States.

[6][2] After redshirting his first year at Miami in 2014, Njoku played in all 13 games with four starts in 2015 and had 21 receptions for 362 yards and one touchdown.

[8] After the season, Njoku decided to forgo his remaining two years of eligibility and enter the 2017 NFL draft.

[20] in the Week 2 game against the Baltimore Ravens, he had three receptions for 27 yards and his first NFL touchdown in the 24–10 loss.

[23] In Week 2, Njoku was upended and landed on his head and left the game against the New York Jets due to a concussion.

[28] Njoku was placed on injured reserve on September 14, 2020, with a knee injury, a day after he posted three catches for 50 yards and a touchdown against the Ravens.

[31] In Week 5 against the Los Angeles Chargers, Njoku caught seven passes for 149 yards and a touchdown, with the score coming off a 71-yard catch and run, in the 47–42 loss.

[37] On September 30, 2023, before Week 4, the Browns announced that Njoku was questionable due to suffering burns on his face and arms in a "freak accident" in his home.

On September 29, 2023, Njoku suffered burns to his face and arms during a household accident where he was trying to light a fire pit.

[41][42][43] He was named a Nigerian chief in his familial village, Umuozu, in Nwangele, Imo State in the 2022 offseason.