Companhia de Seguros O Alentejo, was founded on November 18, 1918, in Elvas, where it had its first headquarters at Rua de João de Pereira de Abreu, nº 19. The insurance company started its activity with branches in Lisbon, Oporto , in the autonomous regions of Madeira and the Azores, as well as in Madrid.

In 1974, Companhia de Seguros O Alentejo had branches and delegations in the main district capitals in mainland Portugal, Angola, Mozambique, Cape Verde, São Tomé, Macau and Timor.

In 1980 Alentejo was merged with Companhia de Seguros Império.