Walden is originally from New Plymouth and was schooled at Francis Douglas Memorial College in his hometown where he played first XV rugby. During his schooldays, he was selected in the schools side alongside future teammate Jackson Hemopo. He moved south to Dunedin to attend university and at the same time began working his way through the rugby structures; he was a member of their academy, played for their age group sides and also turned out for Southern in the local Otago rugby competition.
Senior career
His first taste of senior rugby came with the Otago Razorbacks in 2013, making 5 appearances including 1 start as the men from Dunedin finished as runner up on the Championship log before being defeated by in the semi-finals. In 2014 he established himself as a regular with 9 starts and 2 tries in what was a disappointing season overall for Otago, culminating in a 6th-place finish out of 7 teams. 2015 was much more positive for both Walden and the Razorbacks with him starting 9 times and scoring 1 try and Otago finishing 3rd on the log before being comprehensively defeated by in the semi-finals. He was again in fine form during the 2016 Mitre 10 Cup scoring 2 tries in 11 games as the Razorbacks finished 1st on the championship log before surprisingly succumbing to in the tournament final which consigned them to another season of championship rugby in 2017.
Super Rugby
Some impressive performances in an under-performing Otago side brought him to the attention of Dunedin-based Super Rugby franchise, the who named him as a member of their wider training group for the 2015 Super Rugby season. 2015 was to prove to be a memorable year for the Highlanders who lifted the Super Rugby titlefor the first time in their history, while for Walden, the presence of midfield backs such as Malakai Fekitoa, Richard Buckman, Jason Emery and Shaun Treeby meant he had to spend the year kicking his heels on the sidelines. His Super Rugby debut came the following year in week 1 of the competition, a 33-31 defeat away to the Blues. Overall he scored one try in 6 matches while still a wider training group member in 2016 and new Highlanders head coach, Tony Brown saw fit to promote him to the full squad for 2017.
