Coaching junior hockey
Juujärvi started coaching in the Kärpät junior organization in 1997-98 as an assistant coach for the U14 team. His first head coaching position was with the Kärpät U13 team in 1998-99. Moving up to the head coaching position of the Kärpät U16 team, his team won silver medals in 1999-00. From Kärpät, he moved to the Tappara junior organization. At the helm of the Tappara U20s, the team was crowned Jr. A SM-liiga champion in 2003-04. Juujärvi returned to Tappara U20s in 2017.

Coaching in the pro ranks
After his first stint with Tappara, Juujärvi moved to coach LeKi, a Suomi-sarja promotee, in its inaugural season in Mestis. Finishing in the fifth place in the 2007-08 regular season, his work with LeKi earned him a position as an assistant coach with Ilves in 2008-09. After three seasons in the Ilves organization, he moved to coach Mestis team KooKoo in early 2012. His stint with KooKoo proved successful, earning him a full range of medals: bronze, silver and gold. His time with KooKoo culminated in winning the Mestis championship in 2013-14 and securing the team a right to Liiga promotion. From KooKoo he returned to coach LeKi, developing among others the then 16-year-old Patrik Laine in 2014-15. After his latest stint with LeKi from 2014-15 to 2015-16, he worked as a Finnish Ice Hockey Association tutor coach before being hired to coach RoKi in February 2017. He returned to pro hockey in 2021.