Following the successful operational use of the C-4C by the Portuguese Air Force, Spain selected the aircraft in the early 1970s to reinforce its tactical strike and ground-attack capabilities. The type was adopted as a cost-effective and reliable solution suited to Iberian operational requirements and Mediterranean operating conditions.
A total of 36 C-4C aircraft were delivered to the Spanish Air Force (Ejército del Aire), where they served primarily in the fighter-bomber role. Spanish-operated C-4Cs were adapted with national markings and minor avionics changes, while retaining the original airframe and weapon systems. The aircraft proved effective in training, air policing support and strike exercises, benefiting from its robust design and ease of maintenance.
The C-4C remained in active Spanish service until its withdrawal in 1990, when it was replaced by more modern multirole fighters. Its service marked one of the earliest large-scale adoptions of a Portuguese-designed combat aircraft by a neighboring European air force.