The court ordered authorities "to take all measures" to keep Vincent Lambert alive, pending a review by the UN Committee on the Rights of Persons with Disabilities.
Lambert's mother, Viviane, 73, hailed the latest ruling as "a very big victory" in her struggle to keep her son on life support.
"They are going to restore nutrition and give him drink. For once I am proud of the courts,"she said.
The 42-year old quadraplegic has been in a vegetative state since a motorcycle accident in 2008 and the ruling marks a dramatic reversal in the case.
Doctors in France had earlier Monday halted the nutrition and hydration Lambert receives, following an earlier judicial ruling in accordance with the wishes of his wife and other relatives.
France deeply divided over the right-to-die
The high-profile Lambert case has deeply divided France, where euthanasia is illegal but doctors are allowed to put terminally ill patients into deep sedation.
Lambert's family are in disagreement over how he should be cared for. His wife, six of his siblings and his nephew have repeatedly called for his feeding tubes to be withdrawn but his devoutly Roman Catholic parents and two other siblings remain adamant life support should continue.
Lambert’s wife did not comment on the latest ruling, but his nephew Francis, said restoring treatment would be “pure sadism by the medical-judicial system”.
Before the latest court ruling, Pope Francis weighed in Monday in favour of keeping Lambert alive.
“Let us always safeguard life, God’s gift, from its beginning until its natural end. Let us not give in to a throwaway culture,” the pontiff said.
Calls for President Macron to intervene
On Monday evening, several hundred people gathered in Paris to ask President Emmanuel Macron to exercise his “presidential grace”. This followed an open letter published over the weekend in which Lambert's parents asked Macron for help.
"Mr President, Vincent Lambert will die without hydration in the week of 20 May if you do nothing and you are the last and only one able to intervene," read the letter.
Macron rejected the calls to intervene, saying "the decision to stop treatment was taken after continual dialogue between his doctors and his wife, who is his legal representative".
Vincent Lambert: la Cour d'appel de Paris ordonne la reprise des traitements pic.twitter.com/XNiyBDIzb5BFMTV (@BFMTV) 20 mai 2019
Meanwhile Jean Paillot, one of the lawyers for Lambert's parents, hailed the Appeal court ruling as "a victory" and only "the first". But he drew criticism on social media when he described the ruling as "a remontada" - a term associated with FC Barcelona’s victory over PSG in 2017.
Asked on BFMTV whether he wasn’t ashamed of using the word he admitted it “perhaps wasn’t the most appropriate” but put it in the context of the enthusiasm he felt at the time and his own football culture.
The Vincent Lambert case in five dates