The 37-year-old was arrested by Surrey Police on suspicion of drink driving and failing to stop after a injury accident.
The woman, aged in her 30s, was struck just before 3am near the slip road at Junction 13 Staines-upon-Thames, Surrey, of the M25.
Police are investigating why the unnamed woman came to be on foot on the four laned section of the motorway. She was pronounced dead at the scene.
A black Volkswagen Golf believed to be involved in the collision was found stopped nearby.
The anti-clockwise section of the motorway between junctions 14, Heathrow, to 12, Chertsey was closed as police accident investigators carry out a detailed examination of the scene.
The road has been reopened to traffic.
A spokesman for Surrey Police said: "He remains in custody and will be interviewed later today."
" We are appealing for anyone who saw the female pedestrian walking in the area or along the motorway prior to the collision, or anyone who witnessed the collisions, to contact the Collision Investigation Unit."
The man has been bailed and is due to return to Staines police station on Thursday, February 19.
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