Walmsley, who took over from the sacked Phil Moss on an interim basis in March, has earned a contract until the end of the 2015-16 season and will also continue to serve as the Gosford side's technical director.
In a statement released on Tuesday, the Mariners' former National Youth League-winning coach admitted he had to consider whether or not he would be able to meet the needs of the club, who have gone from champions in 2012-13 to strugglers this term.
"When [executive vice chairman] Peter Storrie asked if I would consider taking the head coach role at the Mariners I needed to weigh up the opportunity carefully," he said.
"It is an honour to be invited to take on the role, but I needed to be clear about my commitment to success, identify what success looks like and how I can make a difference."
A host of players who have gone on to bigger and better things have been developed by or played for the Mariners, including current Socceroos Mile Jedinak, Mathew Ryan, Trent Sainsbury and Oliver Bozanic, as well Mustafa Amini, Bernie Ibini and Tom Rogic.
According to Walmsley, the club will make no secret of its need to produce players capable of attracting supporters to Gosford Stadium before earning transfer fees by moving overseas.
"The club's mantra is entertainment, youth and community," he said.
"As technical director I was brought in to deliver a football program aligned to the commercial objectives of the club.
"This means a recruitment charter that identifies players with embedded talent that can be identified, contribute on the pitch, developed and sold. No hiding behind it. Something to celebrate."
The Mariners' performances have improved somewhat under Walmsley's brief tenure, which included a 1-0 win at home to Western Sydney Wanderers on Saturday.
It remains to be seen though if he can deliver on his stated objectives of challenging the squad to grow and test themselves.
"As head coach I'm interested in exposing players to a style that stretches them beyond where they think their capabilities are and to get the staff to buy into the broader vision," he said.
"Can we be more resilient, yet more expressive? Pretty on the eye? Courageous on the ball, can we be recognised for innovation?"
Thank you for reading 5 articles this month* Join now for unlimited access
Enjoy your first month for just £1 / $1 / €1
*Read 5 free articles per month without a subscription
Join now for unlimited access
Try first month for just £1 / $1 / €1