There were five different scorers for the Blues on the night, but it was Jorrel Hato who provided the crucial opener in first half stoppage time.
Tosin Adarabioyo put Chelsea two up just after half-time before Miles Leaburn halved the deficit for Charlton.
Five minutes later, Marc Guiu scored for Chelsea and confirmed their progress with two more stoppage time goals from Pedro Neto and Enzo Fernandez.
Story of the Match
Charlton Athletic made four changes to the team who drew 2-2 with Blackburn Rovers on Sunday.
Meanwhile, there were eight alterations to the Chelsea side who lost 2-1 to Fulham on Wednesday night.
As expected, Charlton began the game with a lot of energy and were encouraged by a good home atmosphere at The Valley.
After the game was paused due to a medical emergency in the crowd, however, it was Chelsea who began to take more control.
There were some good opportunities for Moises Caicedo and Facundo Buonanotte to shoot from the edge of the box but their hesitation on multiple occasions allowed Charlton to close them down.
On the whole, the game was a very narrow affair with both teams attempting to crowd the midfield.
That said, it was Jamie Gittens on the right wing who stood out and became the main attacking outlet for the Blues.
He found his way past opposition wing-back Tyrese Campbell several times but was often kept from creating any significant chances by a covering centre-back.
The hosts continued to prove tough to break down as the half progressed and, despite their dominance in possession, there were few clear opportunities for Chelsea.
They eventually became more willing to shoot from distance as Josh Acheampong and then Gittens forced Will Mannion into two good saves.
In the fourth of seven added minutes, Jorrel Hato ultimately broke the deadlock for Chelsea. Caicedo’s cross was knocked into his path by Marc Guiu and he finished well on the half volley.
Charlton made a fast start to the second half but, down the other end, Chelsea appealed for a penalty for a possible trip on Buonanotte but the referee ruled that Lloyd Jones had won the ball.
The visitors did not dwell on the decision, however, and doubled their lead not long after when Tosin Adarabioyo headed home from Buanonotte’s free kick.
Down two goals, the Addicks adopted a more attacking approach and got a goal back quickly through Miles Leaburn whose deflected effort flew beyond Filip Jörgensen.
With Charlton chasing an equaliser, there was also more space for the Chelsea forwards to operate in at the opposite end.
After a poor first half, it was Alejandro Garnacho’s cross which initially allowed Buanonotte to get a shot away. Marc Guiu followed in on the rebound to restore Chelsea’s two goal advantage.
Despite lacking a goal or assist, it was an impressive display from Gittens playing out of position, before he was replaced by Estêvão - a change met by even more excitement from the travelling Chelsea fans.
As the mist descended on London, Chelsea continued to press home their advantage, looking to increase their lead.
Estêvão lived up to his enthusiastic welcome and created some good chances for himself, carrying the ball into the box from the right flank.
At the other end, it was Charlton’s turn to appeal for a penalty but the referee decided there was not enough contact from Enzo Fernández on Jones.
Pedro Neto’s near post finish on the 90 minute mark looked to be the final Chelsea blow to seal the win until Mannion brought down Estêvão in the box.
Fernández added a fifth from the penalty spot to put the icing on an ultimately comfortable victory in Liam Rosenior’s first game in charge of Chelsea.
They will be in the fourth round draw, which takes place on Monday evening.
Jorrel Hato's strike opened the scoring for Chelsea. Source: Ben Stansall - AFP.
The young defender was asked to play a difficult role in Rosenior’s first game in charge - one often occupied by the vastly more experienced Marc Cucurella.
His opening goal came from his consistent desire to make runs into the box as an inverted left-back.
The opener was very important for Chelsea who were becoming frustrated by Charlton. Hato then continued to make the same runs in the second half, offering a constant presence in the box throughout the match.