"Yes, undoubtedly. This is a choice of life. But the question rather is 'Will you stay in Barcelona?' Yes… but it does not mean that I will have no more connection to France, I will be returning regularly," Valls told the BFMTV broadcaster after being asked whether he would leave politics if lost the election in Barcelona.
Valls said he would run in the race as an independent candidate on September 25.
Earlier in the day, supporters of Catalonia's secession blocked high-speed railway traffic between the region and France.
Manuel Valls served as French prime minister between March 2014 and December 2016.