The Belgium star needed just six first-half minutes to erase an early deficit and later returned to seal his treble from the spot as the hosts continued their perfect start to the new season.
Cardiff did fleetingly threaten an almighty upset thanks to Sol Bamba's shock 16th-minute opener before Maurizio Sarri's men took command on the way to a convincing fifth straight victory.
The in-form Hazard instigated a hasty turnaround that became a comfortable three points when Willian curled home seven minutes from the end, ensuring the Blues inched into top spot on goal difference.
Neil Warnock's pre-match promise not to "shut-up shop" took shape when Bamba stunned an expectant Stamford Bridge crowd, prodding in defensive partner Sean Morrison's header.
Neil Etheridge twice denied Mateo Kovacic an immediate response but could do little about Hazard's unerring bottom-corner finish that restored parity.
The comeback was complete a minute before the break as Olivier Giroud's gorgeous cushioned touch freed his team-mate to force a second in off Bamba at close range.
Cardiff remained in with a chance of extracting something from the match until substitute Willian arrived to end the resistance, first drawing a Bamba challenge that Hazard converted from the spot in the 80th minute, and then delightfully getting himself on the scoresheet by picking out the top right corner three minutes later.
4 - Eden Hazard is the fourth player to score more than one Premier League hat-trick for Chelsea (also Didier Drogba, Frank Lampard and Jimmy Floyd Hasselbaink). Iconic. #CHECAR pic.twitter.com/Ad743K4o4F— OptaJoe (@OptaJoe) September 15, 2018
What it means: Resilience essential to new-look Chelsea
Chelsea's excellence in possession across the opening few weeks may have masked what seems genuine strength of character. This was a different test to those they had faced against Arsenal and Newcastle United and they passed it with complete comfort, refusing to panic after falling behind for the first time this term.
Pat on the back: Giroud relishes fresh start
He might not have been on the scoresheet here, but the recalled Giroud justified his selection with two telling assists for Hazard that turned the match around. The striker looked rich in confidence following his drought-breaking goal for France last weekend as a pair of delicate touches late in the first half sliced open a Cardiff defence that until then appeared in good order.
Boot up the backside: Kovacic the concern
Hazard's rescue act, hasty though it was, would not have been needed had Croatia international Kovacic made the most of his two earlier opportunities. The midfielder should certainly have converted the second, a one-on-one with Etheridge, and his difficult afternoon came to a frustrating end five minutes into the second half as he limped off with an apparent muscle problem in his right leg.
Key Opta stats:
- Chelsea have won their opening five games to a Premier League season for the fourth time after 2005-06, 2009-10 and 2010-11 – more than any other team in the competition.
- This is the first time that Cardiff have opened an English top-flight campaign without winning any of their first five games since 1921-22.
- Cardiff boss Neil Warnock has gone 11 Premier League games without a win as manager for the first time (W0 D5 L6).
- Cardiff are winless in seven matches in all competitions (W0 D3 L4), their worst run under Neil Warnock; they last went on a longer run without victory between January and February 2015 (eight games).
- Since his Premier League debut in August 2012, Chelsea’s Eden Hazard (115) has been directly involved in more goals than any other midfielder in the competition (74 goals, 41 assists).
- Chelsea striker Olivier Giroud provided two assists in a single Premier League game for the third time in his career and first since January 2017 vs Bournemouth.
Chelsea's busy week takes them to Greece on Thursday for their Europa League opener against PAOK, before a less arduous trip to West Ham three days later. Cardiff, meanwhile, do not get any respite from a tough run of fixtures with Manchester City visiting Wales next Saturday.