Police confirmed they were called out to the Wensley Estate in Firth Park at around 12.02am, where they found a man with fatal injuries.
The man died in hospital a short time later.
The man has now been named locally as Sami Alsoori.
His stepbrother, Mohammed Kaid, told The Star that Sami was stabbed to death.
The 57-year-old said: "'I heard someone had been stabbed and then a bit later in the morning we found out it was my stepbrother.
"I still can't believe it. He was a good dad and no harm to anybody, he's had a very hard life.
"The police haven't spoke to me yet. He has family all over and his sister has just come up from Liverpool.
"He has a daughter who is only six years old. I live around the corner from him, just a few doors away. I'm still in shock, it doesn't seem real.
"All I know is he got stabbed and then police rushed him to hospital and that's when he passed away.
"I have never known him be in any trouble before, he has a lot of friends around here and they respected him a lot. He was born in Liverpool but lived in Sheffield since then.
"My step sister is devastated and his mum lives just down the road.
"I have spoken to some of his mates this morning, I know a lot of them.
"Everybody knows a little bit about everyone around here. We help each other out especially when something like this happens. We're all different nationalities but everyone helps everyone. It is getting worse around here it never used to be like this. It's not safe to walk around here you never know what is around the corner. It's going to take a while to get over this."
A murder investigation has now been launched.
A South Yorkshire Police spokesman said: "We are appealing for information after the murder of a 31-year-old man on the Wensley Estate in Firth Park, Sheffield.
The scene in Wensley Street, Firth Park following the murder of a 31-year-old man. Picture: Andrew Roe
"Police were called at 12.02am on Sunday, September following reports that a man had been injured.
"He was taken to hospital but was pronounced dead shortly afterwards. A murder investigation has now commenced."
Anyone with information is asked to call South Yorkshire Police on 101, quoting incident number 3 of September 10, 2017.