Johnson's signing for Essex may have been greeted with cries of 'Mitchell who?', but his name has long since been known in cricketing circles in his native Australia.
Injury ruled him out of his 2006 stint with Essex but in May he was given a full Cricket Australia contract only two years after driving a delivery truck and considering giving up the game because of his fourth back stress injury.
Referred to by Test legend Dennis Lillee as a "once-in-a-generation bowler", there have been high hopes for the tall, left-armer since he was spotted at a Pace Australia camp as a callow 17-year-old.
Fast-tracked into the Academy and the Australia Under 19 team, he has had his progress checked somewhat by that perennial scourge of pace bowlers, the back injury.
Johnson made his one-day international bow against New Zealand in December 2005, a debut remarkable more for the fact that he was a super sub rather than his bowling figures.
But Essex supporters will be encouraged by the words of Shane Watson, Johnson's Queensland and Australia team-mate, who reckons Johnson to have "the most talent I've ever seen in an all-round athlete".
He was named in every squad for the 2006-07 Ashes Test series but was not given a game due to the impressive Stuart Clark, but he was rewarded for his patience with a place in the squad for the Commonwealth Bank one-day series which followed.
He helped Australia retain the World Cup in 2007.