McLeod's new deal runs through the 2017-18 season, while Stuart's agreement is through 2016-17.
The 30-year-old McLeod has 978 career penalty minutes, which are the most in Avalanche history. Colorado General Manager Joe Sakic said McLeod "brings grit, energy and passion to the rink every single day."
Colorado acquired Stuart on July 1 in a deal with San Jose. The 34-year-old has played in 985 career NHL games for San Jose, Boston, Calgary, Los Angeles and Detroit.
Sakic said Stuart is "a steady, experienced defenseman who is a solid addition to our blue line."