Walden (24) was awarded the David Latta Trophy for the best player throughout the season as judged by his peers.
The trophy is voted on by players on a points system for every game.
Walden had a top season for Otago, playing at second five-eighth for an Otago side which showed plenty of energy and endeavour in attack.
The former Francis Douglas Memorial College, New Plymouth, head boy has also been part of a stellar Otago midfield defensive combination with Sio Tomkinson.
Walden captained the side against Wellington in the capital earlier this month, taking over when normal skipper Sam Anderson-Heather left the field.
Walden has played 34 games for Otago since making his debut in 2013.
Walden has appeared for the Highlanders in the past couple of years, although he had had limited opportunities. He had a fine game against the British and Irish Lions this season as the Highlanders recorded a narrow victory.
Walden follows in the footsteps of lock Tom Franklin and utility back Matt Faddes, who won the David Latta Trophy over the past couple of years.
Other awards for the side were handed out last night, with Craig Millar named the best forward.
Walden was named best back, while livewire left winger Jona Nareki was the rookie of the year.
Versatile loose forward Adam Knight was named player of the year, which was separate to the award given to Walden.
Awards for players in other representative teams were also announced in what was something of a stellar year for the Otago union.
For the first time since 2005, the Otago metro under-18 and the Otago metro under-16 teams both won their South Island tournaments.
The Metropolitan under-18 team shared the title in 2005 and won it outright in 2002, while the Metropolitan under-16 side was the sole winner in 2005.
Other winners were:
Otago Spirit (MVP, best forward, best back): Angie Sisifa, Georgia Mason, Sheree Hume; Otago B: Mike Mata'afa, Iakopo Petealo Mapu, Taylor Haugh; Otago sevens: Leroy van Dam, Jerome Harimate, Mitchell Scott; Otago women's sevens: Sam Hollows, Greer Muir, Alena Saili; Otago Maori: Benny Rumble, Ben Whale, Jerome Harimate; Otago Maori Colts: Rwairi Wereta, Hunter Blackwood, Teremoana Hamblin; Otago Maori Women's: Celine Timoko, Grace Schrader, Celine Timoko; Otago Country: Tim O'Neill/Daniel Harding, Simon Lloyd, ; Otago under-19: Slade McDowall, William Kirkwood, George Witana; Otago Sassenachs Colts: Iakopo Petealo Mapu, Nick Henderson, Conor McLeod; Otago Metro under-18: Henry Bell, Joseph Aldrich-Williams, Burns Mills; Otago Metro under-16: Leroy Ferguson, Oliver Griffin, Giovanni Leituala; Otago Metro under-14: Semesi Taieloa, Steve Salalea, Finn McDonald-Page; Otago Metro under-13: Eric Peita, Petalo Amato, Riley Horne; Otago under-65kg: Henry Cleaver, Keegan Ferguson, Ethan Stirling; Otago under-48kg: Hamish Faulks, Will Scurr/Archie McRae, Jack Hazlett/Samuel Waitoa; Otago under-48kg invitational: Thomas Michelle, Hunter Crawford, Josh Peters; Otago Metro under-38kg: Josh Baughan, Nathaniel Sutherland, William Thode; Otago country under-38kg: Josh Smith, Jacob Field, Owain Harris; Otago school girls: Isla Pringle, Gemma Millar, Lily Davies; Otago Country under-18: Liam Turnbull, Zach McKenzie, Brayden Laing; Otago Country under-16: Beau Meehan, Caiden Davidson, Matthew Wilson; Otago Country under-14: Doug Smith, Ben Smart, Oliver Herron; Otago Country under-13: Kodi Cameron, Max McTavish, Blake Dodds.