The unidentified Stagecoach employee, who was driving the X16 Ayr to Kilmarnock service, came to the aid of the vulnerable woman after she appeared to miss her stop.
Passenger Chris Hendry captured the heartwarming moment at lunchtime on Tuesday, just past Hansel.
He said: “He stopped at the next available bus stop and helped her cross the extremely busy A77 and made sure she got the X16 heading back to Hansel.
“Without the driver’s help this would have been a very difficult and dangerous situation for the woman, so a very big well done.
“I hope the driver gets the recognition he deserves for the good deed.”
A spokeswoman for Stagecoach said: “He is a credit to Stagecoach and his decision to help the passenger cross the busy road reinforces what an important role our drivers play within local communities.”