He will join the likes of Ben Smith, Liam Squire, Luke Whitelock, Jackson Hemopo, Waisake Naholo and Tom Franklin in plying his trade elsewhere next season.
Delaney is set to take up an assistant coaching role with Welsh club Scarlets in 2020.
The 45-year-old has been the Highlanders defence coach for the past two seasons, but will link up with Crusaders assistant coach Brad Mooar in Wales.
Mooar is replacing the outgoing Scarlets head coach Wayne Pivac.
Delaney, who coached Canterbury to a Mitre 10 premiership title in 2016, played schoolboy rugby against Mooar in Christchurch, so the pair know each other well.
Highlanders chief executive Roger Clark thanked Delaney for his service in a press release.
''Glenn has been a significant part of our coaching team over the last few seasons and is highly regarded by the players,'' he said.
''His family have remained in the UK while he has been with us and we appreciate the sacrifices Glenn and his family have made over that time.
''We fully understand his reasons for wanting to return to the UK and wish him all the best in his future coaching roles.''
Delaney said he had enjoyed his stint with the Dunedin-based franchise.
''The environment that exists within the Highlanders is very special,'' Delaney said.
''I feel privileged to have been part of it. I have worked with some outstanding men who I have learned from and have hopefully imparted some knowledge to.
''However, the opportunity to reunite with my family in the UK and undertake a good coaching role with a strong club like the Scarlets was too good to turn down.''
Delaney will take up the role at the end of the Super Rugby season.