2009-10: Selected in the first round (20th overall) of the 2009 WHL Bantam Draft by Saskatoon, Ryan Olsen appeared in five games for the Blades and was the leading scorer for the Greater Vancouver Canadians in British Columbia midget major hockey. He had no points and 2 penalty minutes in limited ice time with the Blades. In 38 games for the Canadians he scored 24 goals with 23 assists and had 32 penalty minutes. He added 2 goals with 1 assist and had 20 penalty minutes in five playoff games for Greater Vancouver.
2010-11: Olsen skated in 63 games for Saskatoon in his first full season with the Blades and represented Canada Pacific in the 2011 U17 World Hockey Challenge. Playing for a Blades team that finished first in the East Division, he scored 7 goals with 7 assists and was minus-11 with 39 penalty minutes. Saskatoon was swept by Kootenay in the second round of the playoffs after defeating Prince Albert in six games. Olsen skated in 3 of 10 playoff games and was an even plus/minus with no points and 4 penalty minutes. In six games for third-place Canada Pacific at the WHC he scored 1 goal with 3 assists and had 2 penalty minutes.
2011-12: Skating in a third line role and frequently matched up against the other teams' top forwards in his second season with the Blades, Olsen managed to contribute offensively; scoring 15 goals with 17 assists. Olsen finished the season minus-12 with 64 penalty minutes. Saskatoon finished third in the WHL's East Division. The Blades were swept by Medicine Hat in the first round of the playoffs. In the four game series against the Tigers, Olsen was minus-one with no points and 4 penalty minutes. Ranked 178th in Central Scouting's final rankings prior to the 2012 NHL Draft, he was selected by Winnipeg in the sixth round (160th overall).
2012-13: Obtained by Kelowna in a multiplayer WHL trade with Saskatoon in May 2012, Olsen had a breakout offensive year in his first season with the high-flying Rockets. He was Kelowna's second-leading goal scorer with 32 goals (trailing only Myles Bell's 38) and had 24 assists, both career highs. In 69 games he was +17 and was second on the Rockets with 87 penalty minutes. Kelowna finished first in the B.C. Division and reached the second round in the playoffs. Olsen scored 1 goal with 5 assists and was -5 with 14 penalty minutes in 11 playoff games.