After going scoreless against Leicester, Hazard struck just before half-time at Vicarage Road to send the Blues ahead.
Mateo Kovacic picked up a loose ball in midfield and knocked through to the forward, who rounded Ben Foster and finished with ease to mark his century.
Chelsea's advantage proved short-lived, however, as Roberto Pereyra hit back almost instantly to level matters prior to the break.
But Hazard popped up in the second half to restore the lead, netting a penalty to make it 2-1 on the night and 101 for Chelsea's star.
The Belgian remains 10th on the all-time list of the Blues' top scorers, with Frank Lampard out in front with 211, nine ahead of Bobby Tambling.
Of Hazard's 101 goals for the club, 79 of them have come in the Premier League, with eight having been scored in the Champions League, seven in the League Cup, five in the FA Cup and one in both the Europa League and UEFA Super Cup.
Bournemouth, Newcastle and West Brom are Hazard's favourite opponents in terms the opposition he has the best goalscoring record again during his time at Stamford Bridge, with seven having arrived against each of those sides.
Cesc Fabregas is the Chelsea team-mate with the most assists for Hazard - the Spaniard having set-up the forward seven times during his time with the club.
Hazard will climb to ninth in the standings of the Blues' all-time leading scorers if and when he scores 109 for the club, with George Hilsdon having netted 108 during his spell as a Chelsea player in the early 1900s.
The former Lille man joined Chelsea back in 2012, and has made a total of 322 appearances for the Blues across all competitions.
There has been speculation over his future at the club, however, with a move to Real Madrid having long been mooted as a possibility, with the Belgian himself having admitted his desire to play for the Liga giants .
He has, however, also suggested that he could remain at Stamford Bridge for the long-term, with Maurizio Sarri's side keen to tie the 27-year-old down to a new deal - his current contract expires in June 2020.
Hazard has been deployed in a false nine position by Sarri in recent times and has now scored in three of his last four games for the club.