The 28 year-old, returning from a nine-month absence, did enough for nine of the twelve rounds on the WBN Scorecard to retain his championship at Copper Box.
Judges at ringside were largely in agreement as Saunders secured a 117-112, 117-111 and 115-114 triumph.
After the fight, Saunders’ young son took centre stage to apologise publicly to Monroe for, ‘punching him in the nuts’ at the weigh-in.
Promoter Frank Warren stated Saunders would now be aiming to fight either Gennady Golovkin or Canelo Alvarez next.
On the undercard, it took Anthony Yarde just three rounds to get rid of late replacement Norbert Nemesapati as the light-heavyweight added the Inter-Continental title to his WBO European belt.
Yarde was too strong for Nemesapati as the talented contender pushed to 13-0.
Daniel ‘Dynamite’ Dubois once again lived up to his nickname with an explosive win over AJ Carter to capture the Southern Area title.
The 20 year-old dropped Carter in the opening seconds before finishing the job before the first minute with a crushing right hand.
Carter was knocked out cold and down for several minutes as Dubois moved to 5-0 with a fifth successive early night.
‘Lethal’ Lucien Reid looked good in taking every round of six against Jose Aguilar.
‘Reidy’ out-boxed his opponent and kept his guard down for most of the contest, which said a lot about the threat Aguilar posed.
Super middleweight prospect Umar Sadiq made a successful debut by scoring a 40-36 points win over Lewis van Poetsch, whilst in the same division, Lerrone Richards made it to 9-0 with a convincing 60-53 points win over Ferenc Albert.
Richards floored Albert in the opening round and never looked back as he notched up another victory.
Also on the bill, welterweight Hamzah Sheeraz stopped Duane Green in his first professional contest before 19 year-old Zak Chelli made it to 3-0 with a points win over Adam Jones.
