The Belgium international sealed victory for Spurs in their FA Cup third-round replay in the 66th minute at King Power Stadium.
Earlier, summer signing Son Heung-min broke the deadlock with an 18-yard strike that beat Leicester goalkeeper Kasper Schmeichel.
Chadli has endured an injury-hit season so far after he picked up a problem against Liverpool before struggling to win back his place in Mauricio Pochettino’s side.
However, the Belgian forward appears determined to put that right in 2016 after his first goal of the calendar year.
Great win! Happy with my first goal of 2016, on to the next one 😉 pic.twitter.com/Likey29iPw
— Nacer Chadli (@NChadli) January 20, 2016
The 26-year-old forward scored 11 times and made five assists in 35 Premier League games for the north London side last season.
However, Chadli is facing competition from England’s rising star Dele Alli for a place in Pochettino’s side.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news