Sister Catherine Rose Holzman, 89, had served the church "with dedication and love for many years," Archbishop Jose Gomez said in a statement.
Holzman was a member of an order of elderly nuns involved in a dispute over the sale of their convent in the Los Feliz neighborhood.
Hours before her death, Holzman spoke to television station KTTV , decrying a judge's ruling that cleared the way for the Archdiocese of Los Angeles to sell the convent to Perry.
"To Katy Perry, please stop," she said.
"It's not doing anyone any good except hurting a lot of people."
The singer sought to buy the eight-acre property and its Roman-villa style buildings for 14.5 million US dollars.
Her efforts to buy the hilltop home were stymied when the nuns tried to sell the convent to a local entrepreneur to turn it into a boutique hotel, but a judge ruled in 2016 that the sale was invalid.
The Sisters of the Most Holy and Immaculate Heart of the Blessed Virgin Mary have owned the property for more than four decades but have not lived in the convent for several years.
"I was sad to hear the news of her passing and I have offered a Mass for the repose of her soul," Archbishop Gomez said.
"We extend our prayers today to the Immaculate Heart of Mary community and to all her friends and loved ones."
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