The 39-year-old, who won K1 silver at Sydney 2000, guided the women's kayak class to World and European Championship medals during the last Olympic training style.
He also coached Lizzie Neave, who won World bronze in 2009 and European bronze in 2011 at the London 2012 Olympics where the 25-year-old finished 12th in the K1.
Britain enjoyed their most successful Olympics ever in canoe slalom in London with Tim Baillie and Etienne Stott winning C2 gold and David Florence and Richard Hounslow silver in the same class.
And, a GB Canoeing coach since 2004, Ratcliffe is determined to build on that success and ensure Britain become the very best in the sport as he begins his new role.
"Having been involved in canoe slalom since I was eight years old, first working my way up through the ranks as an athlete, then through the different stages as a coach it is an honour and a privilege to be appointed canoe slalom podium head coach," said Ratcliffe.
"We have a group of highly motivated and talented athletes, a team of exceptional coaches to match, and a world-class facility at Lee Valley where we are creating an elite environment around the athletes.
"We all want to reach the highest levels in this sport and it is important that we build steadily through the Rio cycle by taking it gate by gate, run by run to maximise every session in our pursuit for excellence.
"GB Canoeing's aim is to be the number one canoeing nation in the world and our goal in the canoe slalom programme is to win medals at the Olympic Games in Rio.
"For us the key is operating a programme of continuous improvement in every area, based around exceptional technical skills to enable us to deliver our best possible performances on race day."