Mahmut was thirty-four when he became sultan having spent twenty-seven years in the Cage.  The first two months of his reign were precarious as the mutineers who had demanded the abdication of his predecessor were still very active.  Eventually Mahmut put an end to their activities by having their leader killed along with some 7,000 Janissaries who had supported him.

Mahmut proved to be a weak ruler dependent on the advice of his mother and the chief black eunuch.  By 1733 he had put down other groups of people who plotted against him, killing thousands in the process.  He then closed down all the coffee houses in Istanbul to prevent people getting together to plot against him, and the city became unnaturally quiet.

A treaty ended the war between Turkey and Iran in 1746 and was followed by the longest period of peace in Ottoman history which lasted some twenty-two years.  In this time Mahmut revived the tulip fetes which had been established by Ahmet.  Mahmut wrote poetry and effectively left the governing of his empire to his advisers.

By the autumn of 1754 his health was failing and, returning from the noon prayers at Hagia Sophia one Friday, he apparently suffered a stroke and fell from his horse dead.  He was fifty-eight and had ruled for just over twenty-four years.  He was succeeded by his half-brother Osman III.