The incident happened in Bishopric Court shortly after 9pm yesterday.
A spokesman for Sussex Police said: “Officers are still investigating the circumstances of what happened, but it appears that three offenders went to the address and forced their way in before attacking one of the occupants with a knife. They also stole property from the flat.”
The man was taken to hospital with stab wounds and was in a stable condition this afternoon.
Simon Brodey, 27, who also lives in Bishopric Court, told The Resident: “There are always problems here. It’s like EastEnders – never a dull moment. I’ve got two children and it makes me worried about them. A lot of families live here and we need to get more CCTV.”
A 20-year-old man from Worthing has been arrested on suspicion of assault causing grievous bodily harm. Police inquiries continue.