A pedestrian has been fatally struck by a bus in Perth, with crash investigators appealing for dashcam footage to figure out what happened.

At about 6.15pm yesterday, a pedestrian was hit by a Perth Transit Authority bus turning right onto Wellington Street in Perth's CBD.

The 45-year-old man was critically injured and died at the scene.

The 37-year-old bus driver was not injured and is assisting police with inquiries.

Major crash investigators are asking anyone with any information to call Crime Stoppers.