A 52-year-old man from Cardiff was charged with murdering company director Kingsley Monk at his office in New Inn, Pontypool, South Wales, Gwent Police said.
He will appear at Newport Magistrates' Court to face charges of murder, attempted murder and false imprisonment.
Mr Monk, a 45-year-old father-of-two from Oakdale, South Wales, was killed at the premises of driving agency Driverline 247 on Monday.
Three of his colleagues were taken to hospital for treatment after the incident on a business park and have since been released.
Mr Monk died from "pressure on his neck", a preliminary post-mortem examination revealed.
Police are still looking for a silver handgun in connection with the attack.
Officers have also appealed for information about an RBS black credit card reader they believe was used during the incident, a black laptop bag and a long-sleeved blue shirt.
A man was arrested by police at Newport railway station on Monday evening.
The arrest followed a raid at an address in Penrhos Crescent, Rumney, Cardiff, which ended when the property was found to be empty.
Anyone with information is urged to contact Gwent Police on 01633 838111 or Crimestoppers, anonymously, on 0800 555 111.
