It happened at about 3.20am on Sunday (September 6) at junction 10 for Baldock services and involved a black BMW travelling northbound.
The BMW left the road and the man was pronounced dead at the scene, while three others were taken to hospital.
A woman in her 20s has been arrested and released on bail.
The road remained closed for several hours.
Detective Constable Lewis Stanley of the Bedfordshire, Cambridgeshire and Hertfordshire Serious Collision Investigation Unit said: “This was a tragic incident which has seen one person sadly die and several sustain injuries.
“We’re working to establish what caused the collision and would appeal for anyone who witnessed it, or anyone who saw – or may have dash-cam footage of – a black BMW driving along the A1 just prior to the incident, to get in touch.”
Anyone with information has been asked to email Detective Constable Lewis Stanley at Lewis.Stanley@herts.police.uk.
Alternatively, you can call Bedfordshire Police on 101, or visit beds.police.uk, quoting Operation Brunswick.