A 19-year-old man was arrested near Stamshaw Park on suspicion of attempted murder.
Superintendent Steve Burridge said: “It goes without saying that our thoughts are with our officer and his family this evening. He is currently in a stable condition in hospital."
Hampshire Police have confirmed that a police officer was stabbed in the back in Portsmouth.
The officer was on patrol along Newcomen Road in Stamshaw Park when he was stabbed at about 12.20pm.
He has been taken to hospital for treatment, although his injuries are not life-threatening. His next-of-kin have been told about the attack.
Police are looking for the weapon that was used to stab the police officer.
Police are also urging witnesses to submit mobile phone footage that could help with their enquiries.
Detectives say they do not believe there is any wider risk to the community at this time.
Investigations are ongoing.