Guei was borne in Kabakouma, a village in the western Man region, he was a member of the Yakouba tribe. He was a career soldier, under the French administration he was trained at the Ouagadougou military school and the St Cyr academy. He was a firm supporter of Félix Houphouët-Boigny and in 1990 he was made chief of the army following a mutiny. Following the death of Houphouët-Boigny in 1993 Guei became distanced from the new leader Henri Konan Bédié. Guei's refusal to mobilise his troops to resolve a political struggle between Bédié and Alassane Ouattara in October 1995 led to his dismissal. He was made a minister but sacked again in August 1996 and forced out of the army in January 1997.
Bédié was overthrown in a coup on Christmas Eve 1999. Although the coup was not led by Guei, the popular general was encouraged out of retirement to head the junta until the next elections. In the October 2000 elections Guei was defeated by Laurent Gbagbo of the Ivorian Popular Front but he refused to recognize the result and it took a spate of street protests to bring Gbagbo to power. Guei fled to Gouessesso, near the Liberian border, but remained a figure in the political scene, he was included in a reconciliation forum in 2001 and agreed to with-hold from undemocratic methods.
Guei withdrew from the forum agreement in September 2002 but was killed in the Cocody district of Abidjan, during an attempted coup . His wife and the interior minister, Emile Boga Doudou, were also killed.