The 28-year-old striker netted after just a minute, bundling in the ball after Toto Nsiala's header came back off the post.
Steven Hewitt's second-half effort forced home keeper James McKeown into an impressive save as Grimsby hung on.
Victory saw the Mariners move to within 10 points of second-placed Forest Green in the National League.
Grimsby Town manager Paul Hurst told BBC Radio Humberside:
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"A great three points on the back of Friday night. We couldn't have got off to a better start and I thought for the first 15 minutes we were excellent but fair play to Southport I thought they came back into it.
"The lads stood strong and it's a really good three points for us.
"We won the game and it's just a case of us trying to keep our shape and discipline which was good. We've just got to try and look after the ball better."
Padraig Amond scored his 27th goal of the season to hand Grimsby a narrow win over Southport at Blundell Park.