The 25-year-old Cruden replaces lock Craig Clarke, who left to play in Ireland, while Messam retains his co-captaincy.
"Aaron has been a massive influence in our success to date," Chiefs coach Dave Rennie said on the team's website.
"His rugby knowledge, attitude and ability to direct a game is impressive. He is greatly respected, a natural leader and will thrive with this added responsibility."
Cruden, capped 29 times for New Zealand, won the Chiefs' Player of the Year award in both years of their back-to-back championship seasons in 2012-13.
Messam, 29, has also been a driving force behind the Chiefs' success, and was voted most valuable player in last year's title decider against the Canberra-based ACT Brumbies.
Favourites to win a third consecutive championship, the Waikato-based Chiefs will play fierce rivals, the Crusaders, in a blockbuster opening round clash on February 21 away in Christchurch.
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