Emergency crews were called to Delhi Street just before noon for reports of the collision.
Police said the man was hit on the road by a passing bus and suffered a “self-contained head injury.” He was taken to a trauma centre in Hamilton, where he is listed in stable condition.
Delhi Street was closed for several hours for the investigation, making it difficult for commuters to access the hospital entrances.
The road reopened at around 2:30 p.m.
Any witnesses who have yet to speak with a police officer are asked to call investigators with the traffic unit at 519-824-1212 ext. 7514.