Saints are now officially safe from relegation and can look forward to another season in England's top flight thanks to Exeter's win at London Irish on Sunday.
The Chiefs crushed their hosts 45-5, meaning basement side Irish remain 14 points behind 10th-placed Saints with just two games to go.
Irish can still technically catch Worcester, who are nine points above the team propping up the table.
But Northampton will not be caught thanks to their superb 27-21 win at Leicester Tigers on Saturday and Exeter's Madejski Stadium success a day later.
Saints have two games remaining during this campaign with the April 29 trip to Wasps followed by a home clash with Worcester on May 5.