The 21-year-old joined the Gunners from Brazilian side Fluminense in 2011, but the English club have been forced to loan the Brazilian to four different teams after struggling to secure a work permit.
Silva has previously spent periods with Levante, Alcoyano, Ponferradina and Real Murcia, but will represent Almeria in La Liga next season.
"A deal has been agreed between Arsenal and Almería for Wellington Silva to go on loan for the season," Silva's agent Alex Soares told Sky Sports News.
"He had the chance to go to a number of teams in Spain, but Silva has decided to join Almería."
Silva scored three times for Murcia last season.