The former Chelsea player is set to have a medical today ahead of completing a £6.2m (Dh30.2m) move to the Etihad Stadium.
That fee could rise to £8m depending on add-ons.
Sinclair, 23, is understood to have agreed a four-year deal with the English Premier League champions.
Meanwhile Swansea have also agreed a fee of around £5.5m to sign Spain international Pablo Hernandez from Valencia.
Chelsea have joined Manchester City in the hunt for France international Loic Remy. Read our full story here.
Spain midfielder Javi Martinez has moved to Bayern Munich in what is thought to be the highest ever transfer for a Bundesliga club.
The 23-year-old has been a Bayern target for weeks, and last night completed his transfer from Athletic Bilbao for a reported EU40million (Dh184.2m)
The player had a release clause with Athletic for that sum - but he was responsible for paying it himself, adding huge tax liabilities as a result.
"Without question, that was a complicated transfer," admitted Bayern chairman Karl-Heinz Rummenigge with the transfer window set to close on Friday.
"So we are very happy that Javi Martinez is finally with us."
The Euro 2012 midfielder, who has signed a five year deal with the European Cup finalists, is due to be unveiled later today.
Fulham are closing in on a move for Dimitar Berbatov afer a day of transfer drama and snubs in Serie A. Read the full story here.
The player's future had been in doubt after the two sides reached a stalemate in contract negotiations, and with just a year left to run on his current deal, the Emirates Stadium side were ready to cash in on the England winger.
However, it is understood that while Walcott did not back down over his contract demands, he gave assurances that he definitely wanted to stay with the Gunners in the long-term.
Arsenal had been braced for the prospect of selling Walcott before the transfer window closes on Friday but they are now happy to continue negotiations beyond then and effectively risk losing him for nothing next summer.
The 22-year-old Spaniard has joined the Rossoneri until June 30, to bolster a front line missing the loss of Zlatan Ibrahimovic to Paris St Germain and Antonio Cassano to city rivals Inter.
He is expected to make his debut in Saturday's Serie A match against Bologna.
Aston Villa have completed the signing of Middlesbrough left-back Joe Bennett.
The 22-year-old England Under-21 international has signed a four-year deal with the English Premier League club.
Bennett completed his move to Villa Park after the two clubs agreed an undisclosed fee, believed to be around the £2.5million mark.
Marseille coach Elie Baup has confirmed the club are in talks with QPR midfielder Joey Barton.
The 29-year-old has been linked with a loan move to the Ligue 1 outfit in recent weeks, having been frozen out at Loftus Road.
Baup told OM's website: "Joey Barton is in the building. I don't know if it will be finalised today or how it will turn out.
"He has to be part of the project, respect the team rules and work in the greater interest of the team. He must comply with these standards.
"His career indicates that he knows that already. And a player of character is often necessary."
Bayer Leverkusen have signed goalkeeper Michael Rensing on a one-year contract.
The 28-year-old former Bayern Munich stopper joins on a free transfer after spending last season at relegated Cologne.