The win keeps Roslyn level with Caversham on 31 points with a game in hand in the Otago Daily Times Premier League. Dunedin Technical is seven points behind with two games in hand.
The Plainsmen showed their teeth with two shots that rebounded off the Roslyn woodwork as Al Rickerby and Regan Coldicott demonstrated their firepower.
In reply, Mike Eisenhut showed his class with some dazzling runs and Sean Brand drilled a couple of shots at Mosgiel keeper Pat Howell.
However, in difficult wintry conditions, both defences were dominant, as Terry Boylan, Tom Kent and Liam Dunbar allowed little space. For Mosgiel, Colin Falvey, Mike McGarry, Tom Bekkers and Phil Langley were steady.
Both sides worked the ball around probing for weaknesses. Mosgiel's Rickerby and Coldicott used the wings well but lacked penetration in the middle.
Brand set standards for Roslyn with tireless running, and a goal was well deserved when Mosgiel failed to clear a centre, and the young Scot pounced on a deflected clearance to ram Roslyn ahead after 35min.
Shots by Ben Keat and Eisenhut went close to increasing Roslyn's lead, and from midfield Taylor pushed forward to good effect, showing his power in the air at set plays.
McGarry also pushed forward in an attempt to create something with Phil Kelly and Shayne Danielson, but for the most part Roslyn keeper Peter Evans was untroubled.
After a spell of Roslyn pressure produced a string of corners, Taylor lost his marker on a near post run, and directed a powerful header downwards past keeper Howell in the 70th minute.
Roslyn used the 2-0 cushion to try and play possession football, and on the bobbly surface had some close calls.
With defenders calling for offside, Rickerby broke on the left wing and drilled over a low cross that caused hesitation among Roslyn defenders allowing Coldicott to show aggressive pace and flick in a well-taken goal at the near post.
Caversham bounced back to form with a 6-0 demolition of Green Island in which the scorers were Darren Overton (2), Tom Jackson (2), Tim Cook and Robbie Deeley.
A hat trick for Greg Chitty spearheaded Northern's 6-1 win over Spirit FC, and University notched its first win since April, beating Grants Braes 4-2.
