The man, who is an employee at the hospital, is suspected of having stabbed a colleague in the chest with a pair of scissors at around 8am on Sunday.
Witnesses spotted the bloodied man outside of the hospital premises on Sunday morning and called the police.
The man was subsequently arrested shortly after 10am at St.Göran's psychiatric clinic in central Stockholm.
Police reported that the arrest passed off without further incident.
According to media reports the man is also suspected of having taken a stranglehold on another man at the hospital shortly after the scissor attack.
"One has been stabbed in the chest, the other he has grabbed by the throat," Jonas Palm at Stockholm police told the Aftonbladet daily.
Patients at the hospital were locked in for their own safety while police conducted their search for the suspect.
The victim in the stabbing attack was meanwhile left nursing chest wounds.
The man was taken to Karolinska Hospital in Solna where he is being treated for his injuries. He is reported to be in a stable condition and remained conscious throughout the transfer.