Sibley came through the Surrey academy and scored a double-century against Essex aged just 17, before turning down a three-year contract to move to Warwickshire, where he was promised greater opportunities.
He has piled on runs in the County Championship and made 11 first-class centuries since moving to Warwickshire.
Sibley remained close with many of his former Surrey team-mates and has friends and family in south London that always made a return to the capital possible. He is set to join on a long-term deal, although there was interest from Hampshire.
That would reunite him with Surrey captain Rory Burns, with whom he opened for England. Where it leaves the out-of-contract Ryan Patel, another academy product who has excelled since moving to the top of the order, is unclear.
Sibley won the Championship at Warwickshire last year, but was dropped after two years in the England side. He averaged a tick under 29 from 22 with two centuries, in Cape Town against South Africa and at Old Trafford against West Indies.
He declined to be part of the England Lions tour of Australia this winter to work on – and expand – his game. He scored his second century of the season this week at Northampton, and has 481 runs at an average of 44 this season.
Warwickshire are busy in the transfer market this year, with Ed Barnard joining from Worcestershire this morning.
Moeen Ali and Saqib Mahmood are also expected to join from Worcestershire and Lancashire respectively, while England fast bowler Olly Stone is among their out-of-contract players.