One of the top organizations in NASCAR, JGR had yet to have any of its four drivers win until Hamlin took the lead with 33 laps left and held off the hard-charging Larson on the final lap.
Hamlin needed his 30th career Cup victory to secure a berth in NASCAR's version of the postseason and end a winless streak that stretched to last September at Richmond.
"Definitely needed a win for the organization, for myself," Hamlin said.
Larson had a sensational run from the rear of the field, where he was forced to start because he failed inspection after he won the pole. Larson lost his points lead last week and his crew chief was suspended after failing a post-race inspection at Kentucky.
Hamlin crashed the No. 11 Toyota in practice and was forced to race in a backup car. It seemed to suit him just fine at New Hampshire.
JGR won seven of the first 12 races last season and
"It's not from a lack of trying," Hamlin said.
JGR also announced this week that Erik Jones would replace two-time
Larson was second and nearly caught Hamlin — after a trying week where NASCAR caught Larson's Chip Ganassi team trying to tinker a bit too much outside the rule book on the No. 42 Chevrolet.
Larson's team was penalized 35 points this week, erasing what had been a one-point advantage over Truex in the driver standings. Truex, who led 137 laps, leads the standings by 38 points over Larson.
Larson's pole-winning time was disallowed because of an unapproved rear deck fin lid.