
After a difficult first half that saw the Kingfishers go into the break 2-1 down, six second-half goals completed a dominant opening league fixture of the season.
The match featured a hat-trick from Dan Macdonald and a resilient comeback from the visitors to secure all three points and move top of the league.
Wattsville's Eduardo Santos gave the hosts the lead in just the seventh minute, putting Monmouth behind against the run of play.
A corner in the 13th minute brought the game back level thanks to a header from Taylor Street.
Macdonald's delivery to the near post was met by Street, who powered his header home to equalise.
Town ramped up the pressure and their chances of finding a second goal looked even more promising when Wattsville's John Mbustshu was temporarily sin-binned for dissent.
However, moments before half-time, the Kingfishers' hard work was undone as The Ville capitalised on a free-kick, with Olaf Rutkowski finding the net.
Town had it all to do in the second half as they searched for a route back into the game.
It did not take long for the scores to be level again, with Callum Uttley making it 2-2 following another set-piece.
Macdonald's corner was delivered deeper this time and found Jack Meredith on the edge of the area. Meredith's effort fell kindly to Uttley, who calmly guided the ball into the net.
The Kingfishers took the lead in the 68th minute after the hosts conceded a penalty. Macdonald stepped up and converted confidently into the bottom-right corner.
Ten minutes later, Monmouth's No.10 grabbed his second of the evening with an outstanding long-range volley that caught the goalkeeper off guard.
Macdonald completed his hat-trick in the 81st minute to further extend Town's advantage.
Toby Prettyjohn made it 6-2 in the 88th minute before Taylor Street rounded off the scoring in the second minute of added time to complete a remarkable second-half turnaround.
Speaking after the game, Team Manager Mark Morris said: "I thought we played really well throughout the whole game. We had to dig in a couple of times after conceding a goal against the run of play to start with, and we didn't really deserve to go in 2-1 down at half-time.
"Our quality came through in the end and there were some really good goals in the second half, Macca's particularly. All in all, it was a good performance and a good introduction for Connor [Street] and Toby [Prettyjohn], who got a goal as well."
The Kingfishers are back in action on Tuesday with a trip to Sifil in Gwent Premier League action.
The draw for the first round of the Gwent Premier League County Motors Challenge Cup will take place on 18 August, with Monmouth set to face Brynmawr United away from home.
Furthermore, Monmouth have been drawn against Taffs Well in the second round of the FAW Welsh Cup qualifiers.