© GettyThe attacks happened at four different locations across Birmingham city centre
The 27-year-old suspect was arrested at an address in the Selly Oak area of the city at about 04:00 BST, West Midlands Police said.
Police said he was also being held over seven counts of attempted murder.
The attacks happened at four different central Birmingham locations over 90 minutes in the early hours of Sunday.
© West Midlands Police
Officers were first called out just after 00:30 on Sunday at Constitution Hill, where a man sustained a superficial injury.
About 20 minutes later they were called to Livery Street, near Snow Hill railway station, where a 19-year-old man was critically injured and a woman was also hurt.
At 01:50, police were sent to Irving Street, where a 23-year-old man suffered fatal injuries and another was seriously injured.
Ten minutes later, they were called to Hurst Street, in the city's Gay Village, where a 32-year-old woman was critically injured and two men were less badly hurt.
Police say they are treating the attacks as "random" at this stage.
"We issued CCTV footage of the suspect and had a strong response from the public. I'd like to thank everyone who shared our appeal and who provided information to the investigation.
"Clearly this is a crucial development but our investigation continues."
A hotline number and website have been set up for members of the public to provide information, while the streets involved remained closed on Monday morning as investigations continued.
Streets were closed on Sunday while investigations took place, and remained closed into Monday morning
"I run a warden service in the city and they stand down at about midnight but that night it had been quite busy so we were getting them taxis from a local venue at about 1:30 to 1:45.
"We heard the screaming then a lot of people running and went outside to see what was going on.
"[It was] a bit of chaos really, lots of people milling around, people around the injured parties, there was a man and a couple that had been injured, a man covered in blood, there was a girl on the ground who appeared to be bleeding quite profusely, people trying to help her.
"Then it was a case of standing back and we were doing our bit really to help with crowd control and to try and get everyone out of the area so the emergency services could do their job."
Julia Robinson described seeing "chaos" on Sunday night
Birmingham MP Shabana Mahmood said she "shares the same concerns as everybody else", but the priority was supporting the police with their investigation.
She said: "There will be a more appropriate stage to have a more forensic sort of detail about the way that the incident unfolded, and also the police response, and I will certainly be asking those questions as well.
"But for now I'm encouraged... the police have described a strong response to their CCTV footage appeal."
'Trap'
West Midlands mayor Andy Street told BBC Radio 4's Today programme it was not right to say the police response was too slow.
"It's very easy to comment on a police investigation while it's live. I don't intend to fall into that trap," he said.
"[There are] lots of questions as to what happened during that two-hour period, but there's people making lots of assumptions from things that they quite frankly don't know."
He also said what happened in the early hours of Sunday "does not define Birmingham".
"We have to see it as a one-off random [incident], and what will define the city is our response to it now," he said.
Nikita Denton told the BBC how she helped a victim
Video posted on social media shows a number of emergency service vehicles at the scene
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