Niedzwiecki was forced to retire aged 28, after battling numerous injuries. He later became a coach at Chelsea, eventually leaving the club in November 2000 after the arrival of new boss Claudio Ranieri. Niedzwiecki then linked up shortly after with Arsenal, succeeding the late George Armstrong as reserve team coach. He also worked as a part-time coach with Wales, under new manager Mark Hughes during this time. In September 2004, he joined Blackburn Rovers, again under Hughes, as a first-team coach. When Hughes left for Manchester City four years later, he was among several at Blackburn who followed him to Manchester.