The result means that Almeria are still in the bottom three, but are now just two points from safety. Espanyol, meanwhile, have dropped into 11th position.
Stuani's jubilation turned to despair in the early stages of the second half, however, as the forward was handed his second yellow card for a late challenge on Fran Velez.
Almeria made use of their one-man advantage 20 minutes from time when Velez headed an equaliser, before on-loan Liverpool midfielder Suso found the top corner with a free kick to leave the away side with a 2-1 lead after 73 minutes.
Espanyol pushed for a leveller in the latter stages, but could not make the breakthrough and their frustration boiled over once more in stoppage time when David Lopez was dismissed to leave the home side with nine men.