As a university professor Gnonsoa worked with Francis Wodié, trying to ensure multiparty poliics in the Ivory Coast. She was a founding member of the Ivorian Workers' Party (PIT) in 1990. She was the second national secretary of PIT, and later the party's first vice president. From 2003 to 2005 she served as Minister of the Environment, representing PIT in Seydou Diarra's government of national unity after the First Ivorian Civil War.