The 28-year-old will be available to face The Magpies at Meadow Lane on Saturday and has worked with Hatters boss Joe Kinnear before, when he played for him at Wimbledon.
Jupp has come in to replace the injured Emmerson Boyce, who could be ruled out for the rest of the season after being told he needs an operation on a groin muscle tear.
Meanwhile, Kinnear has also confirmed that he will offer young midfielder Michael Leary a new two-year deal to stay with the Bedfordshire club.
