The incident happened at Calder Junction on the A720 this afternoon.
Emergency services managed to assist the man.
There is no information on his injuries at this time but a police spokesman has confirmed he is still alive and in hospital.
Traffic in the area was brought to a complete standstill and the A720 was closed in both directions between Baberton and Hermiston.
Traffic Scotland warned long delays were expected in the area and on alternative routes at the time.
A police spokeswoman said: "Officers attended the A720 Edinburgh City Bypass at Calder Junction at 2.40pm after reports of a man fallen from a bridge.
"Enquiries are still ongoing and the man has been taken to hospital."
If you, or anyone you know, needs help dealing with mental health problems, the following organisations provide support:
CALM, www.thecalmzone.net, 0800 585 858
Heads Together, www.headstogether.org.uk
Mind, www.mind.org.uk, 0300 123 3393
Papyrus, www.papyrus-uk.org, 0800 068 41 41
Samaritans, www.samaritans.org, 116 123