Ross Barkley, Kenedy and Mason Mount on two occasions were the goalscorers for the Blues as Frank Lampard's men beat the Royals despite conceding first.
Frank Lampard made several changes as he played the fringe players from the start, with Danny Drinkwater and Tiemoue Bakayoko getting starts at the Madejski.
But Chelsea didn't start well, and the hosts were rewarded for their good start. Josh Barrett's shot bounced back to him and he lobbed Willy Caballero to put the hosts ahead.
Despite a poor opening 20 minutes from Chelsea, Ross Barkley continued his fine form in pre-season. A free-kick on the edge of the box was set up for the midfielder, and he curled it into the top left-hand corner to level the scores. That's two in two for Barkley after his goal against Barcelona in Japan.
Loader then had a chance to put the Royals ahead but he lashed his effort over, but Caballero would have had it covered.
Olivier Giroud then missed an absolute sitter 10 minutes from half-time. Barkley whipped in a free-kick, and Giroud had a free header. But he opted to go to the near post, but his header went wide of the goal.
But it was Kenedy who put Chelsea ahead. A pot shot from range swerved and made it tricky for the keeper and the Blues went into the break ahead.
20 changes were then made between the two sides at the break, with either manager making 10 changes to their side.
The hosts were then level early on in the second-half after poor defending from the Blues. Morrison got away from his man, and he tapped home to level it up again.
Mason Mount, another star performer in pre-season, continued his fine form as he bagged two goals in a matter of minutes.
The first a delightful shot from the edge of the box, which fired into the back of the net. The second was slightly easier as it was an absolute gift. Walker in between the sticks for Reading passed it straight to the 20-year-old who tapped it home to make it 4-2 to Frank Lampard's side.
Baldock pulled one back for the Royals but it remained 4-3 to Chelsea in what was their third win of pre-season, with two to play.
Lampard would've been pleased with individual performances, however defending still needs to be worked on ahead of the new season.
Next up for Chelsea is Salzburg in Austria next Wednesday, and then to Germany next weekend.