[4] Sources: At San Jose State University, Ihenacho played five seasons with the Spartans football team under coaches Dick Tomey (2007 to 2009) and Mike MacIntyre (2010 to 2011).

[1] Ihenacho entered the Spartans in 2007 as the youngest player on the team and ended the year with 32 tackles, the most for a San Jose State freshman since 2004.

In 2009, Ihenacho made 89 tackles, the second-most in the team that year, and tied his individual game high of 12 on October 10 against Idaho and November 21 against Hawaii.

[14] In four games, Ihenacho made 10 or more tackles, including a season high 11 each against Idaho and Utah State.

With San Jose State down 27–20 in the fourth quarter, Ihenacho recovered a blocked point after touchdown and took the ball to the end zone for a defensive two-point conversion.

Ihenacho signed with the Denver Broncos as an undrafted free agent following the 2012 NFL draft on April 28, 2012.

Ihenacho made one assisted tackle in his second game of the season, November 4 (Week 9) in a win over the Cincinnati Bengals.

[28] In the 2013 offseason, Ihenacho began turning heads, showing very good cover skills and run stopping abilities.

In the first released depth chart, Ihenacho climbed all the way to the number two spot for strong safety, pushing Mike Adams for the starting job.

In the Broncos' first 2013 preseason game against the San Francisco 49ers, Ihenacho was in with the starters and led the team with 7 tackles, one being for a loss, and also had a forced fumble, which Rahim Moore recovered.

On September 5, 2013, Ihenacho started his first NFL game at strong safety against the Baltimore Ravens.

On September 15, in the Broncos' 41–23 win over the New York Giants, Ihenacho hurt his ankle in the fourth quarter and was carted off the field.

[29] On October 6, in a game against the Dallas Cowboys, Ihenacho recovered a fumble by Dez Bryant, forced by rookie teammate, Kayvon Webster in the 51–48 win.

[35] By the end of training camp, he beat out Jeron Johnson for the starting strong safety position.