The 58-year-old Maitland man was taken to hospital for mandatory testing and arrested following the fatal bus crash in the state's Hunter region.
He was charged with ten counts of dangerous driving occasioning death and will appear in court on Tuesday, NSW Police said in a statement on Monday.
Police began the grisly task of removing and identifying bodies trapped under the bus.
Acting Assistant Police Commissioner Tracy Chapman described a frantic scene for those who arrived at the crash site at a roundabout on Wine Country Drive near Greta in the Hunter Valley about 11.30pm on Sunday.
"Emergency responders ... were able to smash the front windscreen of the bus in order to pull some people out," Ms Chapman said on Monday.
Ten people were confirmed dead and 25 were taken to hospital with varying injuries, including one person who remains in a critical condition. There are fears the toll could rise.
The bus was returning guests from a wedding reception at Wandin Estate winery in Lovedale to Singleton, about 30 minutes away.
Mitchell Gaffney and Madeleine Edsell, who are highly involved with local AFL club the Singleton Roosters, have been identified by media as the newly-weds.
The Warrandyte Cricket Club in Victoria, where Mr Gaffney is understood to have lived until 2017, said a number of its members were involved in the crash.
By mid-morning on Monday, 21 people remained in hospital, a spokeswoman for NSW Premier Chris Minns said.
One is in a critical condition at John Hunter Hospital, where eight others are stable.
Five patients are in a stable condition at Maitland Hospital, five are stable at Calvary Mater Newcastle and two are in a stable condition at Sydney's Royal Prince Alfred Hospital.
Ms Webb confirmed the bus was righted about 3.30pm on Monday and described the rescue efforts as a delicate operation.
It was possible the death toll would rise if more people were found trapped under the bus or if those with injuries worsened, Ms Chapman said.
A number of crash survivors freed themselves and walked to get help.
Others were trapped under the bus and some had limbs severed, a NSW Ambulance spokeswoman told AAP.
Singleton Mayor Sue Moore said the close-knit community would be deeply affected by the tragedy.
"It will go on for weeks and months trying to heal from this," she said.
An investigation swung into gear following a large-scale emergency response.
Cessnock Mayor Jay Suvaal told ABC News there was "a lot of fog around" at the time of the crash.
Resident and local business owner Peta Hughes said the roundabout where the crash occurred had been under construction for several months, with traffic reduced to one lane.
The bus is owned by Linq which provides school runs and charters.
Its fleet of buses are all fitted with seat belts, the company's website says.
A crime scene has been established and is being examined by specialist forensic police and the Crash Investigation Unit.
Mr Minns said support was being provided to people affected by the tragedy.
"This has been a terrible, terrible event in the history of NSW - and I think today is a day to hug someone that you love and remember how precious life is," he said.
For a day of joy in a beautiful place to end in such devastating loss was cruel and unfair, Prime Minister Anthony Albanese said.
"People hire a bus for weddings in order to keep their guests safe and that just adds to the unimaginable nature of this tragedy," Mr Albanese said in Canberra.
"The mental scars of this will not go away."
NSW Police Minister Yasmin Catley described the situation as unfathomable and an unnecessary loss of life.
19°C