Match ends, Gillingham 0, Barnsley 1.
Barnsley boss Lee Johnson celebrated his first game in charge with a win as the Tykes sealed all three points against Gillingham.
Conor Hourihane had the best chance of a quiet first half when his long-range effort just missed the target.
The visitors took the lead after Ben Pearson's shot was parried by Stuart Nelson and George Waring fired home.
It was a frustrating afternoon for the Gills which was summed up when John Marquis fired over the bar late on.
Johnson, who joined Barnsley this week from Oldham, ended Gillingham's eight-game unbeaten run and sealed a third straight win for the Tykes.
Barnsley head coach Lee Johnson told BBC Radio Sheffield:
"We're delighted. A victory, a 1-0 win away from home, a clean sheet, a perfect result.
"I thought the boys were fantastic, very spirited. Of course it was difficult, blowing a gale against a side that's really in-form.
"We had to come and do a job. The midfield five worked their socks off, big George [Waring] worked hard up front and got his rewards with a goal."
- 31HoyteSubstituted forGalbraithat 81'minutes
- 2GarmstonSubstituted forMartinat 57'minutes
- 8HessenthalerSubstituted forNorrisat 66'minutes
- 7LoftBooked at 16mins
- 31O'SullivanSubstituted forBaileyat 87'minutes
- 36PearsonBooked at 45mins
- 41WaringSubstituted forOatesat 90+3'minutes
- Kevin Johnson
- Shots on Target
Second Half ends, Gillingham 0, Barnsley 1.
Corner, Gillingham. Conceded by Martin Cranie.
Attempt blocked. Jermaine McGlashan (Gillingham) right footed shot from the centre of the box is blocked.
Substitution, Barnsley. Rhys Oates replaces George Waring.
Attempt saved. Conor Hourihane (Barnsley) left footed shot from outside the box is saved in the top centre of the goal.
Attempt saved. Jermaine McGlashan (Gillingham) right footed shot from the centre of the box is saved in the centre of the goal.
Hand ball by Luke Norris (Gillingham).
Attempt missed. Doug Loft (Gillingham) right footed shot from outside the box is close, but misses to the left.
Substitution, Barnsley. James Bailey replaces John O'Sullivan.
Corner, Barnsley. Conceded by Stuart Nelson.
Attempt saved. John O'Sullivan (Barnsley) right footed shot from long range on the right is saved in the top right corner.
Foul by Bradley Dack (Gillingham).
George Smith (Barnsley) wins a free kick in the defensive half.
Attempt missed. John Marquis (Gillingham) right footed shot from outside the box is too high.
Substitution, Gillingham. Daniel Galbraith replaces Gavin Hoyte.
Corner, Gillingham. Conceded by Mason Holgate.
Corner, Gillingham. Conceded by Ben Pearson.
Foul by John Marquis (Gillingham).
Lewin Nyatanga (Barnsley) wins a free kick in the attacking half.