The 23-year-old centre-back impressed at the Madejski Stadium last season, making 41 appearances, helping the Royals to steer clear of the drop.
Hector represented Jamaica at this summer Copa America finals in Chile as well as the Gold Cup in the US and Canada.
The young defender could offer Jose Mourinho a back-up option to the likes of John Terry, Gary Cahill and Kurt Zouma, all of whom have been found wanting after Chelsea’s poor start to their Premier League title defence.
Chelsea have failed to keep a clean sheet this season and have conceded nine goals in four fixtures, with Jose Mourinho surprisingly subbing John Terry during their 3-0 defeat to Man City and dropping Gary Cahill at points during the campaign as well.
One wonders if Michael Hector is capable of breaking into the Chelsea first-team set-up this term, whether he is seen more as a short-term stop gap, or whether he is part of a longer-term plan.
The London Evening Standard state that Chelsea have also completed a £2.7m deal for Nantes centre-back Papy Djilobodji.