When Ferdinand VII renounced the Constitution of 1812 and restored his absolute power in 1823, Mendizábal and many other revolutionary liberals went into exile: in the United Kingdom he opened a trade business.

On 14 September he succeeded Queipo de Llano, keeping the Treasury portfolio during a delicate economic situation due to the First Carlist War's military expenses.

[citation needed] The Liberal movement, the Queen Regent and Mendizábal were supported by the new owners of the confiscated properties, though the measures only benefited the big land tycoons.

A few months later a revolt in La Granja made the Queen accept a radical government and the restoration of the Spanish Constitution of 1812.

Mendizábal was appointed Minister of Finance and a series of revolutionary measures were taken: the abolition of tithe and señoríos, freedom of the press, confiscation of the Church properties).