Negotiations between the two clubs had been ongoing for several weeks before Thursday's official announcement. The fee for the option to make the move permanent has not been disclosed by Barcelona.
Yaakobishvili had returned to the Barcelona fold after spending last season on loan at Andorra, where he had a solid campaign in the Spanish second tier.
Barcelona have opted for a fresh loan to allow him to continue his development, with the club retaining the option to either bring him back or sell him outright next summer, depending on whether Almeria exercise their purchase clause.
The move marks the third goalkeeper exit from Barcelona's ranks this transfer window. Inaki Peña was the first to leave, sold to Panathinaikos for around €3m, before Marc-Andre ter Stegen followed on loan to Ajax.
Barcelona's goalkeeping department has undergone a significant overhaul this summer as the club looks to establish a clearer hierarchy behind first-choice Joan Garcia.
Yaakobishvili, born in Budapest, joined Barcelona's academy in 2018 at the age of 12 and progressed through the club's youth ranks before being promoted to the B team.
He has previously represented Hungary at under-17 and under-18 level, and made 21 appearances for Andorra last season in Spain's second tier, keeping three clean sheets. At Almeria, he will compete for the starting jersey with senior goalkeepers Andres Fernandez and Fernando Martinez as the Andalusian club builds a squad they hope can push for promotion back to LaLiga.