Guerrero was born in Ybaroty, a neighbourhood in the city of Villarrica del Espíritu Santo, Paraguay.

While he was studying at the National College in Villarrica he wrote his first verses; during this time he acquired the "Manú" nickname.

In the 1920s he published poems such as "Surgente", "Pepitas" and "Nubes del este" and plays like "Eireté", "La Conquista" and "El crimen de Tintalila".

In his book La poesía paraguaya – Historia de una incógnita, the Brazilian critic Walter Wey writes: "Ortiz Guerrero represented the great courage of being an intellectual in a country without editors, even that of living exclusively from art, since writing poems and playing the guitar were the only things he was good at".

Towards the end of his existence, Manú received his last visitors and friends in the darkest corner of his miserable room, placing the chairs strategically distant from the bed so that they didn’t see him.