The pair are continuing a long-running association with new Potters boss Mark Hughes, who was named as successor to Tony Pulis in May.
Hughes told www.stokecityfc.com: "They're the best at what they do in my opinion. That is why they have worked alongside me for so long. They are both outstanding coaches, while they also have a real understanding of the game and how I like things to be."
Bowen and Niedzwiecki have served under Hughes each time he has held a managerial post, working as part of the backroom staff for the Wales national team - who all three men featured for as players - and then Blackburn, Manchester City, Fulham and QPR before being reunited with the 49-year-old once again at Stoke.
Potters chief executive Tony Scholes said: "Mark Bowen and Eddie Niedzwiecki have been key members of Mark Hughes' backroom team for some time now and he was therefore eager to have them working with him once again here.
"They both have outstanding pedigree as coaches and we are delighted that they have now agreed to join Mark's new team."
Source: PA
Source: PA