French was born in Bruges, Belgium, the second daughter of English parents John Erington French and his first cousin Frances Elizabeth French. She was educated at the secondary school in Geneva, Switzerland. Her older sister, Evangeline F. French had gone to China as a missionary in 1893. Francesca wanted to go to China also, but she remained in England to care for her aging mother. After her mother died, in 1908 she joined her sister in China.
The French sisters were stationed with Mildred Cable in Huozhou, Shanxi and travelled constantly in the surrounding area. They became known as the "trio."  Francesca was the quietest of the three and described as sensitive, sympathetic, bookish, and artistic. After 20 years in Huozhou, the trio believed that the mission should be turned over to Chinese leaders and the three applied to work in relatively unknown, largely Muslim western China. Although there were doubts that women should be assigned to this region their proposal was finally accepted in 1923.
Travels in Central Asia
In 1913, they travelled to Gansu Province, Xinjiang Uygur and the Gobi Desert, and a few years later they adopted a young Tartar girl, a deaf mute, who remained with them when they returned to Britain.
For most of the next thirteen years, in the words of Mildred Cable: "From Etzingol to Turpan, from Spring of Wine to Chuguchak, we ... spent long years in following trade-routes, tracing faint caravan tracks, searching out innumerable by-paths and exploring the most hidden oases. ... Five times we traversed the whole length of the desert, and in the process we had become part of its life"  A reviewer said of Cable and Francesca French's book, The Gobi Desert, that "this may be the best of many good books about Central Asia and the old Silk Road through the deserts of Western China."
In June 1923, all three set out for Central Asia from Huozhou. Travelling 1,500 miles (2,414 km) over the next eight months, evangelizing as they went, they reached Zhangye (then referred to as Kanchow). Zhangye was the last city inside of the Great Wall. A Chinese evangelist was already working there, and at his request they set up a Bible school over the winter. When summer came they were on the road again, following the Hexi Corridor westward, this time with some of the Chinese believers they had trained. They rented houses for themselves and a building for a church in Jiuquan which thereafter would be their base. From Jiuquan they travelled extensively, selling and giving away bibles and Christian literature and extending their range to Tibetan villages in Qinghai province, Mongol encampments, and Muslim towns in Xinjiang province. They studied the Uighur language to communicate with Muslim women, the top priority of their missionary efforts, although it appears that they made very few converts among the Muslims.
The trio were independent, strong-willed, and bold women. Eva French was criticized for giving Communion to her Chinese congregation on Christmas Eve 1924, celebrating Communion being considered a male prerogative. Uncowed by the criticism, Mildred Cable celebrated Communion the following Easter. Their mode of travel in Central Asia differed from the contemporary expeditions of explorers such as Aurel Stein and Sven Hedin who often traveled in large caravans with armed guards. The trio loaded their cart up with religious literature and traversed the Silk Road alone or with a few Chinese colleagues.
The interpersonal relations among the "trio" were that "Mildred was the 'father figure,' Francesca the mother, and Eva the strong-willed, puckish and wonderful child." 
To return to England on home leave in 1926, they travelled via Russian Siberia. After their return in 1928, they took a year-long journey into Xinjiang (then known as Chinese Turkestan), on the way being detained by a Dongan leader, Ma Zhongying, to tend his wounds. In 1932, they made their first journey into the Gobi, where Cable was badly injured by a kick from a donkey.
The trio left China for the last time in 1936 and were unable to return because, in August 1938, all foreigners were ordered to leave Gansu and Xinjiang by the local warlord. Cable and the French sisters retired to Dorset. During her retirement, Francesca was much in demand as a speaker, making several international tours. She and Mildred Cable continued writing.
Cable died in 1952. Francesca died on 2 August 1960 aged 88 in Watford (which was then in Hertfordshire), less than a month after the death of her sister Eva, who died in Sturminster, Dorset aged 91.
- Mildred Cable and Francesca French, Dispatches from North-West Kansu (1925)
- Through Jade Gate and Central Asia (1927)
- Something Happened (1933)
- A Desert journal: Letter from Central Asia (1934)
- Ambassadors for Christ (1935)
- Toward Spiritual Maturity: A Handbook for Those Who Seek It (1939)
- A Parable of Jade (1940)
- The Gobi Desert (1942)
- The Book which Demands a Verdict (1946)
- George Hunter Apostle of Turkestan (1948)
- W. J. Platt, Three Women: Mildred Cable, Francesca French, Evangeline French: The Authorized Biography (1964).
- Benson, Linda, "Missionaries with Attitude: A Women's Mission in Northwestern China." International Bulletin of Missionary Research Vol. 29, No. 4, 2005, p. 184
- Anderson, Gerald H, Biographical dictionary of Christian missions, ISBN 0-8028-4680-7, 1999.
- "Women Missionaries." htt;//womenmissionaries.blogspot.com/, Accessed 16 Apr 2011
- Benson, 183
- Murray, Jocelyn. "Evangeline and Francesca French". Biographical Dictionary of Chinese Christianity. Biographical Dictionary of Chinese Christianity. Retrieved 7 July 2014.
- Mildred Cable, The Gobi Desert, p. 276.
- http://www.amazon.com/dp/1906393125 accessed 14 Apr 2011
- Benson, pp. 185-186
- Benson, p. 185
- Warner, Marina. "Introduction" to The Gobi Desert. Boston: Beacon Press, 1984, pp. xi
- Benson, 186
- Death Index: Volume 4b Page 280
- Death Index: Volume 7c Page 633. http://www.bdcconline.net/en/stories/f/french-evangeline.php, accessed 16 Apr 2011
- Historical Bibliography of the China Inland Mission
- George W. Hunter
- Percy C. Mather
- List of China Inland Mission missionaries in China
- Biography of Francesca Law French
- "Muslims, Missionaries, and Warlords In Northwestern China". Linda Benson.