A 36-year-old man was attacked with a knife in St Mary’s Street just after 6.15pm on Tuesday 10 August.
He suffered serious injuries to his leg.
Police deployed Armed Response team to the scene and carried out a search and arrested a 44-year-old man on suspicion of causing grievous bodily harm with intent.
He remains in police custody at this time.
Enquiries are ongoing.
Inspector Al Dineley from Southampton Central’s Neighbourhood Policing Team said: “We know there was a large police presence in the area last night which may have caused concern amongst some residents.
“We want to reassure you that tackling serious violence and weapon related crime, remains a priority for us.
“We would like to hear from anyone with information in relation to this incident, and specifically, anyone with dash cam footage who was driving through the area at the time.
“Please call 101 and quote ref 44210318142 if you can help.
“We will be carrying out extra patrols in the St Mary’s area today. Please do come and speak with us if you are concerned in any way.”