The US agency upped its expectation for France on Friday, adding that the risks it identified two years ago had not materialised.
But it kept its rating of France's debt at AA, having reduced it from AAA two years ago.
The improvement in the country's outlook is due to the "gradual introduction of growth-enhancing reforms amid ongoing fiscal consolidation," S&P said in its report.
French Prime Minister Manuel Valls welcomed the news.
"Our reforms to improve the economy, our attractiveness, without sacrificing any of our social model are paying off. Let's continue!" he said on Facebook.
S&P's move was "a sign of confidence... in our country's economic and budgetary perspectives", Sapin said.