Mills made his first-class debut for Essex against the Sri Lankans in the tourist match of 2011 at Chelmsford. He made his Championship debut against Leicestershire at Grace Road in July 2011. His figures in the first-innings were 0–51, but in the second innings, he took 3–48. During the winter of 2011, Tymal Mills was named on the England Performance Programme. He began with training at Loughborough as well as camps in North Wales and with the Greater Manchester Fire Department. Mills then went to Potchefstroom, South Africa for three weeks in November on a specialist fast bowling programme. On Friday 16 December, Mills was a surprise inclusion in the 16 man England Lions squad. In 2012 Mills took 5 List A wickets and average of 58.60. He performed better in the Championship, taking 14 wickets at an average of 30.35. In 2013 his form in List A cricket improved, as he took ten wickets at an average of 23.30. However, he failed to kick on in the Championship, taking 11 wickets, three less than the previous season. His performances for Essex earned him another place on an England performance programme, and he took six wickets for the Lions on their tour of Sri Lanka.
Sussex
In 2014 he joined Sussex. He took wickets at an average of 20 in the English T20 competition, and his pace ensured he continued to stand out. He also bowled in the First division of the County Championshipfor the first time, taking 14 wickets at an average of just below 35. In 2015 he was diagnosed with a congenital back condition and as a result, took time out of playing red-ball cricket. He continued to play T20 cricket and took 19 wickets at an average of 18.84.
Since 2016, Mills has played for Quetta Gladiators in the Pakistan Super League. In 2018, he got a contract from Karachi Kings.In 2019, he was picked by Peshawar Zalmi. In 2020, he was picked by Quetta Gladiators again.
In May 2020, Mills joined Pace Journal as an official partner. Pace Journal is a platform which inspires, educates, and entertains fast bowlers and cricket fans around the world. Speaking on his involvement, Mills stated that he had been following the channel for a while and the consistency and quality of content they produce gave him a lot of faith in their vision. He added that the prospect of being involved in a project which helps in giving back to the game, as well as supporting upcoming cricketers, is of huge interest to him.
International career
On 5 July 2016 he made his Twenty20 International debut for England against Sri Lanka, taking figures of 0/22 as England won by eight wickets. Mills was selected for the T20I series against India. He took 1/27 in the first game as England recorded a seven-wicket victory. In the second match, too took figures of 1/36 as India made 144/8, which proved to be a winning score. In the final match of the series he took figures of 1/31 and was then dismissed for a duck as England lost by 75 runs to lose the series 2–1.
