Here are some things to know about the territory.
– Close to the destitute Comoros –
Mayotte is geographically part of the Comoros archipelago, which lies between Madagascar and Mozambique.
But it is politically separate, remaining a French territory after a 1974 referendum in which the other islands in the archipelago decided on independence.
Its proximity to the Comoros, less than 70 kilometres (43 miles) away, has led to an influx of illegal immigrants from that country, one of the poorest in the world.
Usually arriving on small traditional fishing boats called kwassa-kwassa, they make up more than 40 percent of Mayotte’s population.
– France’s 101st department –
Part of the “Perfume Islands” as a producer of ylang-ylang oil from the cananga tree, Mayotte became a French colony in 1843.
In March 2011 it became the 101st French department, or administrative area, in accordance with a referendum two years earlier.
The islands’ population, who are mostly Muslim, has full French voting and citizenship rights. They have a representative in the National Assembly in Paris, 8,000 kilometres away (5,000 miles), and two in the Senate.
Surrounded by a lagoon of 1,000 square kilometres (390 square miles), Mayotte is spread over 375 square kilometres and actually consists of two islands, the main Grande-Terre and the much smaller Petite-Terre.
– Fast-growing population –
Mayotte counted in September 2017 about 256,500 inhabitants, according to French statistics agency Insee.
This is double that of 20 years previously, and it has become the French department with the strongest demographic growth.
It is also France’s youngest department, with one of two residents younger than 17 years. Its number of births shot up by 45 percent between 2013 and 2016.
The population density is the highest on French soil after the Paris region, with 690 inhabitants per square kilometre in 2017.
More than one in two adults in Mayotte were born elsewhere, most arriving illegally from the Comoros.
But it also has many emigrants: one-quarter of its natives live outside Mayotte, mainly in mainland France or on La Reunion, another French overseas territory.
– Relative poverty –
More than four-fifths of the 16-to-64-year-olds on Mayotte could not read and write in 2012, and more than a quarter of the population is out of work, according to Insee.
Income per capita is four times less than the rest of France and two and a half times less than the other French overseas departments.
But Mayotte is rich compared with its immediate neighbours: income per head is 13 times higher than that of the Comoros and 23 times higher than in Madagascar.