Over the past few weeks, the Medical Practitioners Tribunal Service has heard allegations from the doctors' regulator, the General Medical Council (GMC), that Prof Thompson failed on several counts over his care of Martha.
He was the consultant on call on her ward on 29 August 2021 - two days before she died.
The tribunal said it was "evident" that by around 17:00 that day Martha had "several high risk indicators" including her heart rate, blood pressure, breathing and a rising temperature, which "indicated a sudden and significant deterioration".
It said Martha's condition, which included a new rash, justified her being moved to intensive care but "this opportunity was not taken".
Later that evening, Prof Thompson was called at home by a colleague about Martha's continued fever. He had already seen her on his morning ward round, but did not return to the hospital to examine her in person.
Prof Thompson has said one of the reasons he wanted to keep Martha on his ward was not to distress her parents, but the tribunal said this did not justify withholding or delaying her move to intensive care.
The Medical Practitioners Tribunal Service has now decided that Prof Richard Thompson's fitness to practise had been impaired.
The tribunal said this would reassure the public and send a message to doctors about the importance of following the fundamental principles of good care.