Dr Sahruddin Jamal, a Parti Pribumi Bersatu Malaysia (PPBM) assemblyman representing the seat of Bukit Kepong, was sworn in to replace Datuk Osman Sapian as the state's 17th Menteri Besar on Sunday (April 14).
Dr Sahruddin, who is also state Health, Environment and Agriculture Committee chairman, took his oath of office before Johor Ruler Sultan Ibrahim Sultan Iskandar at the Istana Bukit Serene.
He was pictured receiving his appointment letter at the royal palace in a post on Sultan Ibrahim's official Facebook page on Sunday.
Also present at the ceremony was the Crown Prince of Johor, Tunku Ismail Sultan Ibrahim and His Majesty's son-in-law, Datuk Dennis Muhammad Abdullah.
Dr Sahruddin, 44, had replaced Mr Osman, whose resignation was announced by Prime Minister Mahathir Mohamad on April 8, just 11 months after the Pakatan Harapan (PH) alliance stormed to power in the state that was the stronghold of Umno.
Speculation over Dr Sahruddin's possible appointment as the state's next Menteri Besar mounted last week after Mr Osman's absence from the Singapore-Malaysia 9th bilateral Leaders' Retreat in Putrajaya, a day after Mr Osman held a meeting with Tun Mahathir. Dr Sahruddin had served as Mr Osman's official representative at the leaders' retreat.
Dr Sahruddin won the Bukit Kepong seat at the country's general election on May 9 last year after defeating Umno's Mohd Noor Taib and the Parti Islam SeMalaysia's Mohamad Nur Iqbal Abd Razak by a slim majority of 1,273 votes.
He has a medical degree from Hasanuddin University in Makassar, Indonesia, and operated his own clinic in Johor prior to entering politics, the Bernama news agency reported.
His wife Dr Nila Armila Mukdan is also a doctor and they have three daughters.