The 19-year-old son of Saints director of rugby Jim scored a try in his first two matches for Saints and has made a total of nine appearances.
Fellow backs Tom Collins, George Furbank, Rory Hutchinson, Sam Olver and Howard Packman have also signed deals.
As have forwards Will Allman, Sion Bennett, James Fish, Lewis Ludlam, Alex Moon, Jordan Onojaife and Josh Peters.
Of the group, England Under-20 wing Collins, 21, is the most experienced in a Saints shirt, having made 27 first-team appearances.
Scotland Under-20 centre Hutchinson, 20; England Under-20s 21-year-old fly-half Olver; England Under-20 wing Packman, 20 and England Under-20 second row Onojaife, 20, are the others in the group to have played for Northampton's first team.
"The Saints academy is doing its job, identifying and bringing through local talent.
"There are some highly-rated players in that group - some who've already made an impact in the first team such as Tom Collins and Harry Mallinder.
"The challenge for the club and the players is for more of them to make the step up now and break into the match-day 23 - something which has been difficult this season without an Anglo-Welsh Cup."
Northampton Saints centre Harry Mallinder is among 13 youngsters to sign new deals with the club.