Despite having a year remaining on a deal he signed in February, Gibson said it was "the right time" to step down as the Waratahs enter a rebuilding phase with as many as a dozen internationals heading overseas at the end of 2019.

The Waratahs have 12 players in Australia's 28-strong squad that will contest the world under-20s championship final this weekend.

"We've got some absolute gold nuggets here that are going to filter through our system over the next three to four years and it's time for another coach to take them on that journey and really own that process," he said.

"Having been here for seven years, it's time for a new voice, a new direction, a new game style as new players come into the team."

While insisting it wasn't a factor in his decision to leave, Gibson said there was no denying the Israel Folau controversy that dogged the Waratahs' 2019 campaign had "absolutely" taken a personal toll on him.

"Obviously Israel's had an incredible impact not only off the field but also on the field," he said.

"We lost the highest try-scorer in the history of the competition and that has an impact, particularly on the (reduced) number of tries we scored during the season.

"It's been a challenging period leading people through that. The time taken up and invested in that has taken away from rugby and focusing on it.

"I'm certainly challenged by that situation. I'm really proud of how the team's responded to that situation but it has been tiring."

Gibson had ambitions to reunite with Michael Cheika as the Wallabies' new attack coach before former NSW Waratahs playmaker Shaun Berne was revealed as Stephen Larkham's replacement on Friday.

"I've obviously had discussions earlier in the month but that's a decision for Cheik," Gibson said.

Instead the former All Black is now entering the "totally unknown".

"But I'm excited about that opportunity. I love coaching. I love being in rugby so there'll be something there," he said

Gibson was an assistant coach at the Crusaders, far and away Super Rugby's most successful franchise, before joining Cheika at the Waratahs in 2013.

The pair combined to mastermind the Waratahs' elusive first championship the following season before Gibson took over as head coach in late 2015 when Cheika was appointed Wallabies coach.

Gibson, who took the Waratahs to the semi-finals last year, nominated winning the title five years ago as the highlight of his seven seasons at the club.

He will remain at the Waratahs until his successor is appointed.

Australian Associated Press