Northampton secured promotion back to the Guinness Premiership following their 18-8 victory over National League One title rivals Exeter at Franklin's Gardens on Saturday.
Saints, who were relegated last season, guaranteed top spot and a swift return by claiming their 26th successive league win this term. It means second-placed Exeter cannot catch them with four games still remaining, confirming Northampton's Premiership place.
The hooker Dylan Hartley scored two tries, while the wing Paul Diggin also touched down and the full-back Bruce Reihana booted a second-half penalty to start the celebrations.
The sides will meet again in the final of the EDF National Trophy on 12 April.
Jim Mallinder's unbeaten side have scored 1,135 points and conceded just 295 during an impressive season.
But Saints fly-half Carlos Spencer warned that next season will be a far more difficult proposition.
"Next year will be another level to what we've played this year," the former All Black said. "The quality of ball we get in this competition will not be the same next year, because we will come up against a lot bigger forward packs.
"It is definitely a big step up from this division. We can't get too far ahead of ourselves, we've got to be realistic. We've got to look at the long-term goal for this club."Reuse content