The unit was created on 1 May 1937 in Girona, from regular soldiers, militiamen from the Jubert Division, Madrid defense forces and confederal militias from Barcelona and Figueras.

In November 1937 the 136th Mixed Brigade was assigned to the 14th Division in Guadalajara, remaining in reserve, although on 6 December it was again located on the front line, covering the Cifuentes sector.

On 10 February 1938 the brigade faced four enemy assaults against its positions in the Vertice Sierra and Cabezo Cano, managing to repel them.

A few weeks later, between 1 and 6 April, it intervened in a small offensive on the Cuenca front that, however, did not bear the desired results.

At the end of March 1939 the 136th MB withdrew to Madrid, where it dissolved itself.