The CPP'17 conference (Certified Programs and Proofs) is the sixth conference in a series that was started in 2011. The first editions were held in December 2011 in Taipei (Taiwan), in December 2012 in Kyoto (Japan), in December 2013 in Melbourne (Australia), in January 2015 in Mumbai (India), and in January 2016 in St. Petersburg (Florida, USA). The first three editions were co-located with the Asian Symposium on Program Languages and Systems. The last two editions were co-located with the ACM Symposium on Principles of Programming Languages (POPL). This edition is also co-located with POPL'17, in Paris (France). We are thankful to ACM SIGPLAN for sponsoring CPP'17 and to the POPL'17 general chair and local organizers for hosting CPP'17. The CPP conference also received financial support from Inria, France.