Former PC Andrew Bell uploaded one image to the Fab Swingers website of himself in uniform, with his warrant card, and another of him naked.
The 39-year-old officer also engaged in a sexual relationship with a “vulnerable” woman whom he met when she reported her partner for controlling and coercive behaviour.
On Monday, an independent panel at a police misconduct hearing in Wakefield found gross misconduct proven against PC Bell and said he would have been sacked if he had not already resigned.
The panel found PC Bell to have breached professional standards of behaviour for authority, respect and courtesy, and discreditable conduct.
The hearing was told that the pictures on the swingers’ website were discovered after they were seen and reported in an anonymous message from a member of the public in June 2020.
PC Bell, who did not attend the hearing, previously admitted that the Fab Swingers account was his and that both the photographs were of himself.
Mike Percival, a solicitor for West Yorkshire Police, said: “He repeatedly said that he was ashamed, embarrassed and disgusted by his behaviour.”
In the separate allegation, PC Bell went to the woman’s house in the course of his duties following her report of being in a controlling and coercive relationship.
The panel heard that the woman told the officer how her partner had encouraged her to record sexual acts and images and publish them on the internet.
She also told him that she suffered from bi-polar disorder and felt her partner exploited her condition.
Mr Percival told the hearing that PC Bell gave the woman his Instagram account details and, within a short period of time, began an intimate personal relationship, lasting around four to six weeks.
During that time, PC Bell sent sexually explicit images of himself to the woman and received intimate images in return.
The woman later spoke about the relationship to a mental health professional, who initiated a referral to West Yorkshire Police.
Mr Percival said: “He said he could not condone what he had done or provide any sort of defence. He accepted what he’d done looked atrocious.”
He added: “He couldn’t justify any of what he’d done, he was genuinely appalled and guilty.”
The solicitor told the panel the woman had been left “feeling uneasy” and “with the feeling of being taken advantage of” by the relationship.
Marcus Waite, who chaired the panel, said: “We are satisfied on the balance of probabilities the breaches of professional standards of behaviour do amount to gross misconduct.”
Mr Waite said the misconduct was “of such seriousness, with such grave aggravating features” that PC Bell would have been dismissed without notice if he was still employed by the force.
He said: “It would have been the only justifiable and proportionate outcome.”
PC Bell’s name will be placed on the police barred list.
The panel said they were not persuaded that professional standards of behaviour for orders and instructions had been breached.