The 19-year-old, who scored against Bayern Munich on City's pre-season US tour, will head to Deepdale to broaden his experience with a campaign in the Championship.
Nmecha was promoted to the senior squad at the start of last season after impressing at EDS level.
Born in Hamburg, Lukas has been with the Blues for more than a decade, steadily rising through the junior ranks.
He made his senior bow last season away to Leicester in the Carabao Cup, coolly tucking away a penalty in the ensuing shoot-out.
He made two more appearances off the bench against West Ham and Brighton towards the end of the Centurions campaign and featured in every game of the recent US Tour, scoring a first senior goal in Miami against Bayern.
Nmecha has won 27 caps at various England youth levels, scoring seven goals, including the winner in the semi-final and final of England Under-19s’ UEFA European Championship triumph in Georgia.
You can keep a close on his progress in Loan Watch as the season progresses.
Good luck, Lukas!