The surprise announcement was made early on Tuesday morning with the minister saying that he would continue as the MSP for Aberdeen Central, a position he has held since 2011.
Mr Stewart previously served as the minister for local government, housing and planning from 2016, and minister for mental wellbeing and social care from 2021. He was appointed as the transport minister in late March this year.
In his resignation letter to First Minister Humza Yousaf, Mr Stewart said: “Since last October I have had bouts of poor mental health, with a low ebb in early December of last year.
"Over the last week or so I have once again been feeling unwell and I feel that I can no longer put in the hours required to serve both my constituents and hold ministerial office, whilst also trying to maintain good mental health.”
Accepting his resignation, the first minister thanked him for his eight years of service, noting that many people underestimate the pressures faced by ministers and that he had been a “hard-working, loyal and dedicated minister” during his tenure under Nicola Sturgeon and himself.
Mr Stewart was the fourth transport minister since 2020 with Paul Wheelhouse holding the position from June 2018 to May 2021. Graeme Dey then succeeded him until January 2022, and thereafter Jenny Gilruth held the post for three months until March 2023.
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