The 43-year-old male officer was called to check on the welfare of a man living at a home in Portswood Road just before midday today.
He was then stabbed several times and suffered serious, but non life-threatening injuries.
Detective Chief Inspector Dave Brown said: “Our thoughts are very much with the officer and his family at this time.
“We have a man in custody arrested on suspicion of attempted murder and we progressing the investigation, carrying out enquiries, conducting house to house visits and scoping CCTV opportunities.
“At the same time, we are providing support to the officer’s family and his colleagues following this incident.
“I would like to reassure you that we do not believe there is any wider risk to the public.”
The victim’s family have been informed and are being supported by specialist officers.
A 51-year-old man from Southampton has been arrested on suspicion of attempted murder and remains in police custody.
Anyone with information can call police on 101, quoting 44200400513.