After starting his career at
GKS Bełchatów in Poland. Miazek earned a move to Dutch
Eredivisie side
Feyenoord in 2012, where he progressed through the academy.
Chojniczanka Chojnice He joined Polish second division side
Chojniczanka Chojnice from Feyenoord in 2016, he made four appearances for the side in a solitary season at the club, before being released.
Leeds United Miazek joined
Leeds United on trial towards the end of 2017 He impressed and signed a permanent deal at the club in January 2018. He joined the club's academy initially to feature with the Development squad. On 27 June 2018, Miazek signed a new contract at the club. He made his first start for Leeds' first team when he started in their pre-season friendly 1–1 draw against
York City on 20 July 2018, under new head coach
Marcelo Bielsa. On 24 November 2018, after injuries to
Bailey Peacock-Farrell and
Jamal Blackman, Miazek was named on the bench for the first time for the
EFL Championship match against
Bristol City. He returned to the bench on 30 March, for suspended goalkeeper
Kiko Casilla, in the 3–2 home win over
Millwall. After a successful season with Leeds' under-23s, on 6 May 2019, Miazek saved two penalties (from Joe Redmond and
Caolan Boyd-Munce) in a 4–2 penalty shootout (0–0 after extra time) versus Birmingham in the
Professional Development League (Category 2) final.
Jack Clarke then scored the winner for Leeds. On 18 May, Leeds announced that Miazek, together with reserve keeper,
Will Huffer, had had their contracts extended by one year, with the club having taken up an automatic option on their existing contracts. On 13 July 2019, Miazek was one of just 16 players named in
Marcelo Bielsa's 1st team squad for Leeds'
2019–20 pre-season tour of
Australia for matches against
Manchester United and
West Sydney Wanderers. He started the season as Leeds' second-choice goalkeeper after the sale of
Bailey Peacock-Farrell. After the English professional football season was paused in March 2020 due to
Impact of the COVID-19 pandemic on association football, the season was resumed during June, where Miazek was part of the squad who earned promotion with Leeds to the
Premier League and also become the
EFL Championship Champions for the 2019–20 season in July after the successful resumption of the season. Miazek left Leeds in August 2020 when his contract wasn't renewed
Polish lower divisions On 4 August 2021, Miazek returned to Poland and joined
IV liga Łódź club
Warta Sieradz. In his first season with the club, Warta won the Łódź group and earned promotion to the
III liga. In June 2024, he signed a contract with fellow III liga club
Star Starachowice. On 31 July 2025, he moved down a division to join Polonia Piotrków Trybunalski. ==International career==