Abagusi may have originated from a place known to them as Misiri, under their ruler and ancestor called Kwitu.
From Misiri, Abagusi and some Abaluhyia groups migrated to the Mount Elgon region where they lived for several generations.
Around 1500AD, Abagusi, Abakuria and a section of Abalogoli migrated down Nzoyia river valley and settled at Goye in Yimbo and near Ramogi hill and other areas on the eastern shores of lake Victoria.
Due to arrival of Luo Ancestors In the lake region around 1550AD, Abagusi were pushed to Alego, Kisumu, Sakwa and Asembo areas.
Shortly after 1600AD, drought forced Abagusi to migrate and settle in the Kano plains. Their farther migration eastwards brought them into conflicts with the Kipsigis. Because of this, they moved to the fertile Kisii highlands and other parts of their present homeland, such as Kitutu, South Mugirango and others.
In spite of conflicts with the Luo, Maasai and Kipsigis, Abagusi exhibited and practised good interaction, due to which they intermarried, traded and had other forms of exchange with these communities