The 58-year-old driver, George Seger, was leaving a Dunkin' Donuts about to start his morning shift when a stranger approached and slashed him outside the bus.
He had parked near the corner of Queens Boulevard and 69th Street, at around 3:45 a.m.
The suspect wasn't a passenger and he wasn't trying to get on the bus.
He cut the MTA worker with a box cutter, then told the bus driver to call the police, investigators say.
WATCH THE EXCLUSIVE SURVEILLANCE VIDEO BELOW (Slashing at :08, Police make arrest at 1:55)
The suspect stood about 10 feet away from the bus driver and waited for police to arrive.
The suspect also raised the box cutter toward police but was overpowered by the number that responded and quickly arrested, according to police.
The driver, who works out of the LaGuardia Bus Depot, was treated for a deep gash across his stomach at Elmhurst General Hospital. He received 11 stitches and was listed in stable condition.
Responding police officers located 48-year-old Carlos Lema and took him into custody.
Charges are expected.