The two parties first agreed a deal in 2008 and Macron now supply several other English teams.
Leeds United chief executive Shaun Harvey said: "When we first agreed a deal with Macron we were viewed as their flagship across Europe and we're delighted to be able to continue that association for the next six years."
Macron chief executive Gianluca Pavanello said: "Macron is very proud for the extension of the partnership with the club. Leeds was the first club to believe in Macron in the UK."
Source: PA