The actor revealed he was spending his 60th birthday in quarantine after testing positive for the virus, and said that he was experiencing symptoms of fatigue.
Banderas reassured fans that he expected to make a full recovery in the near future.
It is not clear where the actor contracted coronavirus, but, translated from Spanish his post read: 'I feel relatively well, just a little more tired than usual'.
He said he was 'confident that I will recover as soon as possible' from the 'infectious process that I suffer and that is affecting so many people around the planet'.
The actor added that he would be spending his time in isolation focusing on reading, writing and resting.
He said he would 'continue making plans to begin to give meaning to my newly released 60 years to which I arrive loaded with desire and enthusiasm'.
It is not known whether Banderas is in Spain, the US, or England, where he also has a home.