The man, who cannot be named to protect the identity of the child in his care, was caught with 270 illegal images and videos.
Leeds Crown Court heard police raided his home in West Yorkshire and seized two electronic devices, including a Samsung mobile phone.
They found 25 movies and two stills categorized as Category A – the most serious – uploaded.
They also found two category B films and 246 category C images.
Most of the abused children were between three and five years old, prosecutor Louise Pryke told the court.
She said they found “systematic searches” of abuse images on the phone, as well as links to bestiality sites.
The man, who is in his 30s and has never been convicted, admitted three counts of possessing illegal images.
There was no indication that any of the images involved the child he was raising at the time.
Mitigating, Jemima Stephenson said the defendant suffered depression after his arrest and felt genuine remorse for his actions.
She said: “It happened at a low point in his life, he had turned to cocaine and was spending more time on the internet.
“He went from watching legal pornography to accessing this totally inappropriate material.”
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Judge Mushtaq Khokhar told him: “You had a nervous breakdown immediately after your arrest due to concerns about the ramifications.
“Your card has been flagged if there is a repeat of you committing these kinds of offenses of this nature.
“It’s a suspended sentence but next time you won’t be so lucky.
“What you need is help.”
He sentenced him to eight months in prison, suspended for 18 months.
He also received 30 days of rehabilitation and a Sexual Harm Prevention Order (SHPO) to limit his internet use.
The Yorkshire Evening Post contacted the local authority under which the defendant was a foster, to find out whether he had since been struck off.
No response has yet been received.