Dr Paul Hewish, 52, admitted possessing indecent internet images and making indecent pseudo-images of a child on a computer.
He was given a three-year community rehabilitation order at Hull Crown Court.
The images were found by a locum at his practice in Goole, in the East Riding of Yorkshire.
The court heard the relief doctor had shown them to a colleague who then confronted Hewish.
Police then found more than 30 images of young girls at his York home.
District Judge Frederick Rutherford acknowledged Hewish only held a small amount of indecent material.
But he added: "Remember this, your interest in these images help sustain the market and encourage the trade of more vile activities."
Patients' helpline
Craig Sutcliffe, defending, said Hewish, who now lives in Hopton, Norfolk, had brought "devastation" on himself.
He added: "There is no evidence that his actions, which took place in private, in any way affected his professional competency and his competency towards his patients."
A spokeswoman for the General Medical Council, which suspended Hewish in July, said it would now consider his conviction.
A helpline for his former patients has been set up by the East Riding of Yorkshire Primary Care Trust.