Morrison was also shortlisted for the New Zealand job earlier this year, but he has today pledged his future to the Rams.
He said: “I’m very happy to extend my contract and it was an easy decision to make.
“We have a great group of players at this club and I’m really enjoying myself here. It’s the perfect environment for me to continue my development as a head coach.”
Rams chairman Mark Sawyer said he was delighted to be able to secure the services of Morrison, who he appointed as head coach ahead of the 2013 season.
“As we continue to build for the future and plan our recruitment, we knew it was important to stabilise ourselves in the coaching department.
“The players enjoy playing for Glenn and we are very pleased with the results he has delivered since coming to the club.”
Dewsbury travel to face Featherstone in the Championship on Sunday.