After winning silver at the 2005 European Junior Championships, Robbie was thrust into the senior fold in 2006, claiming 4x200m Freestyle Relay silver for Scotland at the Commonwealth Games then making his senior European debut in Budapest later in the year.
He made his World Championship debut the following season in Melbourne before claiming World Short Course bronze over 400m Freestyle in Manchester then reaching the 200m Freestyle final and finishing eighth on his Olympic debut at Beijing 2008.
Having made another World Championship appearance at Rome in 2009, Renwick enjoyed a breakthrough season in 2010, winning his first British title over 400m Freestyle then landing 200m Freestyle gold at the Commonwealth Games in Delhi.
After competing at the 2011 World Championships in Shanghai, Renwick finished fourth over 400m Free at the 2012 European Championship in Debrecen then made his second Olympic final, finishing sixth over 200m Free at London 2012.
Renwick claimed 200m and 400m Freestyle gold for the second consecutive British Championship in 2013 before reaching his first individual World Championship final later in the year, finishing sixth over 200m Free in Barcelona.
He competed at his third Commonwealth Games in 2014, finishing fifth in the 200m Freestyle before winning his fourth career medal for Scotland with silver as part of the 4x200m Freestyle Relay quartet.