A:Answer I am certain it is. I am using it on a Canon 80D and the lens mounts are the same. Be mindful that the 90D has an APS/C sensor - as does the 80D, so the effective focal length of this lens with those cameras becomes something like 225 to 900mm. That having been said, the IS works very well and I have found this lens, while somewhat heavy, to be very sharp. Auto focus seems to be spot-on right out of the box. I am very happy with the way it works on my 80D should not be a problem with a 90D.
