In the wake of Nicolas Sarkozy's victory in the 2007 presidential election, Philippe briefly returned to political life working for Alain Juppé, when Juppé served briefly as Minister of Ecology, Sustainable Development and Energy, before being appointed Director of Public Affairs at Areva, where he worked from 2007 to 2010. He was also substitute to Jean-Yves Besselat, who served as the member of the National Assembly for Seine-Maritime's 7th constituency from 2007 to 2012. In 2008, he was elected to the general council of Seine-Maritime in the canton of Le Havre-5, and in 2010 was elected mayor of Le Havre after the resignation of Rufenacht, his mentor, and also became President of the Agglomeration community of Le Havre the same year. After Besselat's death in 2012 following a long illness, Philippe took his seat, successfully holding it in the subsequent legislative elections. He was reelected as Mayor of Le Havre in the 2014 municipal elections in the first round, with an absolute majority of 52.04% of expressed votes. Following his resignation on 20 May 2017 as Le Havre Mayor, he retained a seat in the municipal council.