Richard Chappell, 44, of Thornhill in West Yorkshire, was messaging officers when he thought he was speaking to parents offering their children for sex.
He was found guilty of attempting to arrange a child sex offence and inciting child exploitation.
His partner, Cherie Scott, 29, was also jailed for sex offences.
The couple were living in the Crigglestone area of Wakefield, between 2016 and 2019 when they committed the crimes, police said.
Chappell exchanged messages with accounts he believed to belong to parents with young children but were actually being used by undercover officers.
He described obscene things he had done and what he wanted to do to the recipients’ children.
After Chappell was arrested in April 2020, his home was searched and police seized lchildren’s underwear and clothes, sex toys and phones and computer equipment containing thousands of images of children.
Scott was caught describing to Chappell on a message how she had committed an offence of sexual touching.
The child involved was later identified by police.
The couple, who lived on King Edward Street in Thornhill, were both given indeterminate Sexual Harm Prevention Orders when they were sentenced at Leeds Crown Court on Friday.
Scott was found guilty of sexual assault of a child and admitted one count of making indecent images and one count of distributing indecent images.
She was jailed for three years and nine months.
Chappell was found guilty in November of 11 counts of attempting to arrange the commission of a child sex offence and five counts of inciting child exploitation.
Det Ch Supt Carl Galvin, head of the Yorkshire and Humber Regional Organised Crime Unit, said Chappell was a “depraved individual will sexual perversions involving very young children”.