Having come through the ranks at Northampton playing for O.N's and Northants Academy, he got his chance in the 2009 season aged 19 after a good pre-season.

He appeared alongside Northants teammate Jack Brooks on Cricket AM feature, Brain vs Brawn, in 2010.

In 2013, Willey helped Northamptonshire to a 102-run victory in a rain-shortened Friends Life Twenty20 Final against Surrey where he made 60 with the bat, then had figures of 4/9, including a match-ending hat-trick to clean up the tail.

In the Scorchers' second match against the Sydney Sixers, he scored one run and didn't take a wicket, in a heavy defeat.

In the third match against the Melbourne he bowled well, taking two wickets with the ball before Ashton Agar scored a six to win in the final over.

[13] In February 2022, he was bought by the Royal Challengers Bangalore in the auction for the 2022 Indian Premier League tournament.

[26] He didn't take a wicket in the first game, but returned with figures of 3–25 in the second match to help England win by 95 runs.

[36] Willey played in the first T20I against South Africa, taking figures of 0–15 and scoring an unbeaten seven with the bat, although England lost the game by 3 wickets.

[38][39] He played a crucial role in the win over Afghanistan, making an unbeaten 20 to guide England to 141, before taking 2–23 with the ball.

[40] In that same match, partnered with Moeen Ali, he set the record for the highest partnership for the 8th wicket in T20 World Cup history, 57 runs.

[44] While Willey bowled well, taking figures of 3–20, England fell just short and lost the game to finish as runners-up.

[48][49][50] In the fourth match of the series, he took figures of 2–58 to help restrict Sri Lanka to 305 and England went on to secure a six-wicket victory.

[52] Willey played in the fourth ODI against Pakistan, although he didn't pick up a wicket and finished with figures of 0–40, although England won the match.

[58] In the first ODI, Willey made an unbeaten ten runs before taking figures of 2–47 as England lost by three wickets.

[69] He scored twenty-one runs and didn't take any wicket in the next match as England suffered their third defeat of the series against New Zealand.

[70] He scored ten runs and failed to take any wicket but England managed to defeat New Zealand this time in their final match of the series.

[71] Willey took a figure of 1–41 and scored an unbeaten thirty-five runs as England defeated Australia in the first match of the ODI series.

[81] On 29 May 2020, Willey was named in a 55-man group of players to begin training ahead of international fixtures starting in England following the COVID-19 pandemic.

[82][83] On 9 July 2020, Willey was included in England's 24-man squad to start training behind closed doors for the ODI series against Ireland.