The 36-year-old left Stamford Bridge after a 13 glittering years upon the expiry of his contract at the end of last season and signed for new MLS franchise New York City.
However, New York will not be in action until March - meaning Lampard faced at least seven months without competitive action.
It had been thought the midfielder could follow New York's other marquee signing David Villa in joining up with Manchester City's second overseas venture, Melbourne City, until the beginning of the 2015 MLS campaign.
But Lampard has instead opted to go back to England, signing until January with the Premier League champions.
"From next Wednesday he will start working with our team and will play for us until January – we'll see after that," City manager Manuel Pellegrini said on Saturday.
"At the moment he will work with the squad and be a member of the squad. He will fight for a position.
"He knows we have a very good team, we have a lot of players in his position. He is one player more. We have a lot of games particularly with the Champions League, so he's very important for our team."
It remains unclear whether Lampard will face his former club Chelsea when the teams meet in the league on September 21.
Lampard, who is Chelsea's all-time record goalscorer, won three Premier League titles, the UEFA Champions League, four FA Cups and two League Cups during his trophy-laden stint in west London.
