The animal escaped from a field and meandered across the carriageway as shocked drivers looked on.
Surrey Police received calls from the public at around 8.35am to say the cow, named as Daisy, was on the anti-clockwise carriageway between junctions 5 and 6 near Godstone.
Rush hour traffic was blocked while the farmer and traffic officers ushered the cow away from the motorway and safely back onto neighbouring farmland.
A traffic data journalist who saw the incident on cameras while at work said: “A cow jumped a fence and got on to the road just after 9am and about 10 police in total were at the scene.
“The police held traffic for about 20 minutes to try to catch it.”
The road was reopened at 9.23am the knock-on from the incident was still causing delays up to an hour later.
Around a month ago there was a similar, yet possibly more extreme, situation on the A2 in Coldred, near Dover in Kent.
Breakdown technician Joe Clift was driving to a job at 5.30am on August 6 when a whole herd of cows suddenly started stampeding down the road towards the traffic.
Many vehicles were forced to stop for a few moments while they waited for the chaos to pass.
Joe, from Medway, Kent, said: ‘I was in pure shock because It’s really strange to see. It was like a weird dream. They were literally sprinting up the road.”