linguistic:paraphrasing, quality:corruption, structural:summarization
21st century

The Requiem Mass of Cardinal Jean-Marie Lustiger, former archbishop of Paris and Jewish convert to Catholicism, was held in Notre-Dame on 10 August 2007.

The set of four 19th-century bells at the top of the northern towers at Notre-Dame were melted down and recast into new bronze bells in 2013, to celebrate the building's 850th anniversary. They were designed to recreate the sound of the cathedral's original bells from the 17th century. Despite the 1990s renovation, the cathedral had continued to show signs of deterioration that prompted the national government to propose a new renovation program in the late 2010s. The entire renovation was estimated to cost €100 million, which the archbishop of Paris planned to raise through funds from the national government and private donations. A €6 million renovation of the cathedral's flèche began in late 2018 and continued into the following year, requiring the temporary removal of copper statues on the roof and other decorative elements days before the April 2019 fire.

Notre-Dame began a year-long celebration of the 850th anniversary of the laying of the first building block for the cathedral on 12 December 2012. During that anniversary year, on 21 May 2013, Dominique Venner, a historian and white nationalist, placed a letter on the church altar and shot himself, dying instantly. Around 1,500 visitors were evacuated from the cathedral.

French police arrested two people on 8 September 2016 after a car containing seven gasoline canisters was found near Notre-Dame.

On 10 February 2017, French police arrested four persons in Montpellier already known by authorities to have ties to radical Islamist organizations on charges of plotting to travel to Paris and attack the cathedral. Later that year, on 6 June, visitors were shut inside Notre-Dame cathedral in Paris after a man with a hammer attacked a police officer outside.