The Brazil international rejoined the Blues on transfer deadline day for £32million after a two-year stint at Ligue 1 giants Paris Saint-Germain.
The experienced centre-half made his second Chelsea debut in the 2-1 defeat to Liverpool on Friday night, their first defeat under new manager Antonio Conte.
Luiz was forced back to first-team action following an injury to captain John Terry, who rolled his ankle in the 2-2 draw with Swansea.
And Hazard has hailed the return of the 29-year-old Luiz, who he believes brings a 'winning mentality' back to the squad.
"Everybody is happy to see [Luiz] back," Hazard told Chelsea TV. "On the pitch he is a warrior. He brings that mentality. He wants to win everything. This is what we need."
Chelsea travel to Premier League champions Leicester in the third round of the EFL Cup tonight looking to get back to winning ways.