A man in his 60s died at the scene after his black Ford C-Max collided with a Volvo Skip Loader vehicle parked in a layby near junction 49.
Police were called to the incident at 23:41 on Thursday 20 February, with ambulance crews and firefighters also attending.
The westbound carriageway between junctions 50 and 49 remained closed for several hours, reopening at 07:30 on Friday 21 February.
Drivers warned to avoid A14 after serious collision
Motorists are being advised to find alternative routes following a serious crash that has closed the westbound A14 between Stowmarket and Haughley.
Officers are appealing for witnesses to the collision and are particularly interested in dash-cam footage from motorists who travelled westbound on the A14 between Felixstowe and Stowmarket after 23:00 on Thursday night.
Anyone with information is asked to contact the Joint Norfolk & Suffolk Serious Collision Investigation Unit, quoting reference 37/9754/25, via the Suffolk Police website, by emailing SCIU@norfolk.police.uk, or by calling 101.
