The man died after falling onto the road at the Scott Arms junction in Great Barr at around 1.20am on Friday.
The motorway was shut southbound since the incident happened until around 4pm, a closure of more than 14 hours.
Meanwhile in an update released at midday, West Midlands Police said they believed they had identified the man and have informed his family.
There were delays of more than an hour as a result of the closure, with around seven miles of congestion back towards Junction 10 as well as slight delays for northbound drivers.
Southbound traffic was diverted around Junction 7 via the exit and entry slip roads while the A34, which goes over the motorway, was also shut.
A West Midlands Police spokesman said: "We were called at 1.23am today to the southbound carriageway at Junction 7.
"Officers from the Central Motorway Patrol Group along with staff from West Midlands Ambulance Service and Highways England were immediately sent to the site. Sadly the man died at the location.
"We’re doing everything we can to identify him so that we can share the awful news with his family."
Nick Baker, regional operations manager at National Highways, said: “Safety is our top priority and the M6 southbound is currently closed at Junction 7 while police colleagues carry out work at scene. We appreciate that road closures cause some disruption but it is important that this work can take place safety following the incident.
“Drivers should allow extra time for journeys if travelling on the M6 this afternoon and we thank them for their patience.”
Anyone with information about the incident is asked to contact police on 101, quoting reference number 162-180322.
The Samaritans can be contacted 24/7 on 116 123 or at samaritans.org