Hazard scored the decisive goal in the 2-0 success at Hull on Saturday, breaking the deadlock just before the hour mark with a trademark run and shot into the bottom corner.
Fernando Torres sealed the points three minutes from time, but there was no doubting Hazard's influence on the result.
Mourinho was left to reflect contentedly on the Belgian international's contribution, which took his season's tally to 10 goals - just five fewer than he managed all of last season.
Hazard arrived from Lille in 2012 with a hefty price tag of more than £30million but Mourinho believes he has since developed from raw prospect to proven performer.
"The club made a big investment on him...to bring a player from France and pay the amount Chelsea did is because Chelsea trusted the player a lot," said Mourinho.
"But he is not a talented kid any more. He is now more than that. He is a player who feels and accepts the responsibility, feels and accepts that a team player is more than a talented player and he has done it without losing his fantastic ability and fantastic talent.
"The kid is in a very good moment of his career."
Mourinho also made an early case for his man to receive individual recognition.
"Three consecutive times he is man of the match, which is something nice. Let's see if the Barclays Premier League decides to give him player of the month," he added.
"Maybe they don't like to go to Cobham because the kid is waiting but the trophy is not arriving."
The 23-year-old playmaker is a reported target of Paris St Germain, who have the resources to tempt most clubs, but Mourinho is on record as saying he would not even entertain a £100million bid.
Hazard also seems happy in his work and told BT Sport: "I am good at this club and I will keep going for a long time.
"We are young, we are in first place (at the end of the match). We are a very good team and a very young team."
Goalkeeper Petr Cech moved into the record books with his clean sheet - a 209th shutout for the club, taking him into new territory and ahead of Peter Bonetti.
Despite that the Czech international is more focused on collective success than personal landmarks.
'The most important thing is that we keep winning games and winning trophies,'' he told BT Sport.
''We want to win the league if we can and hopefully clean sheets will help us achieve our targets. This is the most pleasing thing about winning a very important game."
Hull boss Steve Bruce is hoping some good news on the transfer front will help his side move on from defeat.
"We agreed a fee (for Jelavic) last night. We hope we can persuade him to come here," said Bruce.
"We're trying our best and we'll see what happens.
"We've had a conversation with West Brom about Long's availability at boardroom level but that's as far as that goes at the moment.
"They've appointed a new manager, so I would have thought they would have to have a conversation with him, so we'll see how that develops."
Everton boss Roberto Martinez expects the Jelavic move to happen and says he will leave Goodison Park with his blessing.
The 28-year-old Croatia international scored twice in last week's FA Cup win over QPR but has fallen down the Toffees' pecking order and wants regular action ahead of this summer's World Cup.
Martinez said: "We have agreed with Hull. I had agreement with Niki, that if he could have an opportunity to play between now and the end of the season, and he felt it was the right one, he would be allowed to do that.
"I spoke with him and he feels it is what he needs now, to play before the opener against Brazil in the World Cup.
"I do feel there is going to be an agreement, although they are discussing the personal terms."
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