Keegan Allen is showing the gruesome aftermath of his terrifying armed robbery ... after two masked men allegedly stole his watch and pistol-whipped him.

The "Pretty Little Liars" actor took to his Instagram Stories Saturday to provide an update on his head wound ... sharing a snap of what looks like a couple cuts stitched up.

He also said in the caption he's "Healing" ... adding "thank you to medical team ... and law enforcement and everyone reaching out."

As we reported, Keegan was loading groceries into his vehicle when two men dressed in black approached him around 9 PM. One suspect allegedly pointed a handgun at him while the other brandished a knife, demanding his watch and bracelet.

Surveillance footage shows the suspects confronting Keegan before one appears to repeatedly strike him in the head with a gun. The pair then took off with his watch.

Keegan shared disturbing footage of himself moments after the attack, with blood streaming down his face and onto his clothing as he struggled to explain what had happened.

The actor said the suspects threatened to kill him over his watch, adding ... "My life for a watch."

The Los Angeles County Sheriff's Department previously told TMZ ... Keegan suffered a laceration to his forehead and was treated by paramedics at the scene. He was not transported to a hospital by ambulance, though he later said he went to the hospital and believed he had suffered a concussion.

Keegan also blasted the area's safety, declaring West Hollywood is no longer safe.