The Tigers ended the season with a 4-9-2-1 record.
Ridgefield went into the game needing a victory to qualify for the upcoming Class L state tournament.
The loss was the fifth straight for the Tigers.
Despite not making the post-season, Ridgefield did win two more games than it did last year, when it finished with a 2-6-5-3 record.
Newtown raised its record to 6-9-0-1 with its second straight victory.