Officers received a 999 call just after 1:30pm, with armed police and paramedics attending the scene.
A 32-year-old woman has been arrested on suspicion of grave and criminal assault.
Jersey has relatively low levels of crime compared to other parts of the British Isles, with just two high-profile stabbings this year: one on the Le Geyt estate in January and one outside the Ambassadeur Hotel in March.
A Police spokesperson says the victim is "in a stable condition" and officers believe the two people knew each other:
"Police are currently dealing with a stabbing incident that happened in a residential property in Roseville Street this afternoon.
"The male victim is currently in hospital in a stable condition and police have arrested a 32-year-old woman on suspicion of grave and criminal assault.
"It is believed that both parties are known to each other. The investigation continues."
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