Ighalo, the tournament's top scorer with five goals, tapped in after keeper Moez Ben Cherifia deflected the ball off his own defender Yassine Meriah.

In a slow-paced game between the two losing semi-finalists in Cairo, Tunisia went close as Ferjani Sassi and Ghaylene Chaalali shot wide.

Three-time winners Nigeria have now finished third eight times.

Tunisia, champions in 2004, needed a finger-tip save from Cherifia to deny Samuel Chukwueze in the second half and the keeper was called on again injury time to acrobatically save Samuel Kalu's free-kick.

Senegal will look for their first Afcon title when they face 1990 winners face Algeria in Friday's final.