Eyewitnesses reported hearing “explosions” following the collision in which a van overturned and caught fire, engulfing a lorry and two other cars.
A 49-year-old man from Fife died in the crash, although it is not known which vehicle he was travelling in.
Firefighters arriving at the scene found “numerous people” trapped within their cars.
Police, fire crews and paramedics were called just before 8:50am yesterday to the westbound carriageway near Junction 3 for Livingston. Around 20 firefighters from Edinburgh and West Lothian fought to free the victims and put out the blaze.
Images taken from cars caught immediately behind the crash showed flames consuming three vehicles, producing a thick plume of smoke.
A lorry belonging to UK firm Adelie Foods was left on its side, with images showing the cab surrounded by flames.
A spokesman for the firm, which has its only base in Scotland in Kilmarnock, said it could not confirm the condition of its driver, adding: “We understand that one of our delivery vehicles has been involved in a serious multi-vehicle road traffic accident that took place on the M8.
“Our thoughts are, of course, with all of those people involved in this incident; however, at this early stage we do not have any confirmed details of the cause of the accident, or any injuries that might have been sustained, and therefore are not able to comment further.”
The M8 was closed until yesterday afternoon, with drivers caught in tailbacks for several hours.
Heavy congestion was reported on roads flanking the motorway, including on the approaches to Edinburgh Airport.
One of those caught up in the disruption was city councillor Karen Keil, who said: “We were been sitting on the A8 between Gogarburn and Newbridge for 45 minutes. It was very, very slow because of the crash.
“The other side, going into Edinburgh was just as slow. People were clearly turning around and going back.”
A Police Scotland spokesman said: “Police responded to a four-vehicle collision on the westbound carriageway of the M8, junction 3, at around 8:50am yesterday.
“Two cars, a van and an articulated lorry were all involved in the incident, which resulted in three vehicles catching fire.
“We can confirm that one male has died as a result of this collision and inquiries are ongoing.”
A spokeswoman for the Scottish Fire and Rescue Service (SFRS) said: “The SFRS was called to attend reports of a road traffic collision on the westbound carriageway of the M8 on the approach to the Livingston junction.
“The first appliances arrived within minutes and immediately started tackling a fire involving an articulated lorry, a van and two cars.”