Goals in either half from Andy Adam and Garry Thomson secured the 2-0 win for the Memorial Park side playing their first match since December 4.
Making his 'second debut' after re-signing for the club on Hogmanay was goalkeeper, Ryan Linton, and he played his part in the team recording only their fourth clean sheet in the league this season.
Thornton came close to taking an early lead at The Clayton Caravan Park Recreation Ground when Kieran Dall fizzed in a shot that smashed off the crossbar.
Despite coming close on several other occasions it wasn't until the 26th minute that Andy Adam struck a beauty from 30 yards to give the visitors a deserved lead.
That this was the only goal in the first-half is thanks to Stuart Drummond who was handily placed to head Jake Grady's netbound effort off the line in the 41st minute.
Linton made a great save to prevent Fraser Anderson from snatching a 47th minute equaliser then shortly after at the other end, Garry Thomson smashed a low shot past Kyle Moran following clever play by Dean McMillan.
Joe Kinninmonth must have thought he'd headed home the Hibs' third in the 54th minute only for Nicholas Rendall to make a superb goal-line clearance.
John Soutar came off the bench to make his Hibs' debut and within a minute or so he fired just over from a narrow angle but there was to be no more scoring allowing Craig Gilbert's men to record their second league victory over the Saints this season.
GI Joinery Hibs' Man of the Match: Dean McMillan
St Andrews United: Moran, Anderson, Rendall, C.Sneddon, K.Sneddon, Redpath, Cunningham, McCaulay, Grady, Stanfield, Sawers. Subs: Haleef, Russell, Davidson.
Thornton Hibs: Linton, McMillan, A.Drummond, S.Drummond, Shanks, Adam, Dall, Coleman, Kinninmonth, Thomson, Lamont. Subs: McNeish, Robertson, Daniel Meldrum, Soutar, Doran, Darren Meldrum.
Referee: Mr B.Dickson
This weekend Thornton are on their travels for an intriguing Fife derby away to Kennoway Star Hearts in Conference A.