The 23-year-old had been heavily linked with French champions Paris Saint-Germain, with Laurent Blanc publicly expressing interest in the attacker, though Hazard has since said he is certain to remain in London.
And Mourinho, despite having been critical of Hazard during last season's Premier League run-in, has now confirmed that he has no intention of letting the former Lille man leave Stamford Bridge.
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"He has fantastic potential and will express it at Chelsea. For him, as for others, the door is closed. People who know me know that, when I say that, I mean it."
Hazard was Chelsea's top scorer in the Premier League last season, netting 14 times, while he also made seven assists.
Though the west Londoners have already sold David Luiz to PSG, as well as releasing Frank Lampard and Ashley Cole, Hazard is highly unlikely to join them in leaving Chelsea and is in the process of sealing a contract extension.
"I am staying at Chelsea, [that is] 100 per cent sure," he told Le Derniere Heure on Monday. "I am in discussions with Chelsea for a new contract.
"It is only the beginning of the talks right now so we have got time but the fact that Chelsea have offered me a new deal means that they have got a lot of confidence in me that I can do a good job and that they can count on me."