Jean Ybarnegaray was born in Uhart-Cize, Department of Pyrénées-Atlantiques, then called Basses Pyrénées, in the Northern Basque Country.

He was wounded and discharged from the army with the Legion of Honour, returning to the Chamber of Deputies, where he criticised the Nivelle Offensive of 1917, the armistice of 1918 and the Treaty of Versailles.

A member of the Republican Federation, Ybarnegaray joined the French Social Party of François de La Rocque in 1938.

He served in the French State government in the first cabinet of Marshal Philippe Pétain as Minister for Veterans and the Family.

Ybarnegaray had undertaken French Resistance activities[citation needed], assisting escapees in crossing the Pyrenees, for which he was arrested in 1943 and detained in Plansee in the state of Tyrol.