Monga broke through at Leicester City last season, scoring one goal and providing two assists in around 30 Championship appearances, eight of them starts, before completing a move to Manchester City over the summer.
The teenager had been strongly linked with Arsenal before ultimately choosing City, where he signed a contract running until the summer of 2031.
Swansea head coach Vitor Matos said the club had landed a rare young talent.
"Jeremy is a very exciting young player, one whose abilities are not common in players of his age," Matos said. "He has gained plenty of experience of first-team and Championship football, and has looked confident and shown an ability to effect games at this level.
"We are delighted he and Manchester City have chosen Swansea as the place where they feel he can continue to develop and improve, and we are eager to see what he brings to the group."
Monga made his Premier League debut for Leicester at 15 years old, becoming the third-youngest player in the competition's history, and later became the youngest goalscorer in Championship history when he netted against Preston North End. Manchester City's move for him over the summer was reported to be worth between £10million and £12.5million, reflecting the level of interest he had generated from multiple Premier League clubs before his switch to the Etihad Stadium.
The loan gives Monga a clear pathway to regular first-team football that would have been difficult to guarantee immediately at City, with the Manchester club and manager Enzo Maresca viewing Swansea as an ideal environment for his continued development.
He is expected to return to City for pre-season training ahead of the 2027-28 campaign, with the loan carrying no obligation or option to buy attached.
Born in Coventry, Monga began his development at Coventry City before moving to Leicester's academy in 2024, from where his rapid rise to first-team football at both club and youth international level made him one of the most closely watched teenage prospects in English football.
He has also represented England at Under-19 level, adding to a profile that made his availability on loan a notable subplot of deadline day for Championship clubs monitoring City's academy graduates.
Swansea's attacking options have been bolstered significantly this summer, with Monga joining Elijah Just, Moussa Yeo and Joseph Opoku as new wide additions, giving Matos considerably more depth and variety heading into a season in which the club have made an unbeaten start to the Championship campaign.