Father Fortunato Pantisano, aged 44, who was ordained in 2013 and served at Our Lady of Perpetual Help in Fulham, denied the charge.
However, according to Mail Online, Fr Fortunato failed to convince the magistrates during his trial at City of London Magistrates Court.
In court, he suggested that collection money had been going missing at the church recently, saying: "Because of what had been happening in the previous weeks, I decided to go back to count the money that day."
Fr Fortunato told the trial he could not recall if he had taken any of the collection money.
"I do not remember taking any money. If I did, it was not my intention to be dishonest—it was to buy food, maybe; I don't remember," he said.
The magistrates ruled that his explanations lacked credibility and convicted him of dishonestly appropriating the funds.
The court heard that on 7th January, after the second mass, the priest entered a locked office, removed the collection baskets, and returned them empty.
The incident has caused significant mistrust within the church community, according to a statement from the Diocese of Westminster.
Father Pantisano will be sentenced on 17th September.