Ramsdale was kicked in the back shortly after Arsenal beat fierce rivals Tottenham Hotspur 2-0 in the north London derby in the Premier League.
Joseph Watts pleaded guilty Friday at Uxbridge Magistrates Court to three charges, including assault by beating.
Watts, a Tottenham fan, was also given a community service order and instructed to pay Ramsdale £100 ($120) in compensation.
Watts had climbed over a barrier before kicking the goalkeeper, who had gone behind one of the goals at Tottenham Hotspur Stadium to pick up his water bottle.
Ramsdale in a victim impact statement read to the court said he saw a masseuse because his back felt "heavy." The goalkeeper said he's also wary of similar incidents happening in the future.
Watts has apologized to Ramsdale and both clubs.
"He takes full responsibility for those actions, which were deplorable and which no football player should ever have to endure from a fan," Football Law Associates attorney Robert Perkins, who represented Watts, said in a statement.
"He accepts the punishment of the court and now wishes to move on with his life."