Stoddart, who won eight caps for Wales scoring five tries, was forced to retire in January after failing to recover from a broken leg.
The full back, who played for the Scarlets, Llanelli RFC, Pontypridd and Treorchy, suffered the injury playing for Wales against England in a warm-up match prior to the 2011 Rugby World Cup in New Zealand.
Sadly, the injury forced him into retirement though Stoddart can now look forward to a coaching role at Pandy Park under head coach Greg Woods.
Keys missed out on a play-off place last season and Woods is hoping input from the former Wales man can help his side to climb the table.
"Morgan is a young coach who is fresh out of the professional game and keen to learn," he said.
"He is ambitious, wants to progress in the game and will fit in well here. He will learn from the existing coaching team and we will learn from him.
"Morgan is a down to earth character who is ambitious and I am sure the players will respond to someone who was a quality international player only two years ago."
Stoddart's experience in the Premiership should help to guide some of Keys' younger players, his performances at the semi-professional level eventually seeing him earn both regional and international honours.
"If Morgan enjoys half of the success off the field as he did on it then he will be a superb appointment for the club," said Keys secretary Chris Clarke.
"We spoke to an enormous amount of people about filling the role and Morgan stood out as someone who would be an excellent fit to join our existing set-up."
Stoddart is not the only new arrival at Pandy Park.
Newport Gwent Dragons flanker Jevon Groves has been named as assistant forwards coach and will be in charge of the Keys squad at this weekend's Foster's National Sevens.