Girard leaves the Ligue 1 club following a poor season overall, in which they only managed to finish eighth.
Lille have acted swiftly to appoint Renard, who takes the job having led the Ivory Coast to Africa Cup of Nations glory in Ferbruary.
"This is a day that will count in my career as a coach, but the days that follow this need to be even more beautiful.
"I am very impressed by the Domaine de Luchin training ground and now I cannot wait to start the adventure with the squad.
"It is going to be a very exciting challenge and I go into it with ambition."