Burstow was signed by the Blues in the January transfer window before being immediately loaned back to the Addicks for the remainder of the campaign.
The forward’s temporary deal with Charlton will officially expire on May 31st and he will link up with Chelsea’s senior squad ahead of the 2022/23 campaign.
A product of the Addicks’ academy, Burstow made his senior debut in the club’s EFL Trophy clash with Crawley Town last year.
The forward went on to score against Aston Villa’s Under-21 side, Milton Keynes Dons and Hartlepool United in this competition before attracting the attention of Chelsea who opted to swoop for him.
Burstow played his final game for Charlton last month in the club’s clash with Morecambe.
Despite creating a goal in this fixture, Burstow was unable to prevent his side from suffering a 3-2 defeat to their opponents.
Ahead of his permanent exit from Charlton, the forward has thanked the club’s fans on Instagram for the support that they have illustrated following the announcement of his switch to Chelsea.
Burstow posted: “Dear Charlton Athletic, it’s time to say goodbye, I want to thank you for everything you’ve done for me.
“I signed for Charlton September 2020 on a scholarship and signed my first professional contract July 2021 where I developed as a footballer and as a person whilst gaining lifetime friends along the way.
“This club has given me a platform and many opportunities to showcase myself and develop as a person as well as a footballer.
“I used to be a young local fan who sat in The Valley dreaming to play there one day… that dream came true and I can’t thank you enough.
Quiz: Can you name which English club these 24 ex-Charlton Athletic players play for now?
“Many thanks to all the fans that have had my back from the start and shown nothing but support throughout this season, despite signing for Chelsea Football Club.
“We have had many ups and downs as a family through the year, but we got through it together and I’m sure this amazing club will be back to where it belongs one day.
“This chapter of my life has come to an end and I’m sad to see it go but excited for new beginnings.
“Wishing you all the best, Mason Burstow.”
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It will be interesting to see what the future holds for Burstow as he will be determined to follow in the footsteps of Joe Gomez who has featured on 86 occasions in the top-flight for Liverpool after emerging from Charlton’s youth academy.
The Addicks may not necessarily struggle in the absence of Burstow as they are currently able to call upon the services of the likes of Jayden Stockley and Chuks Aneke.
Aneke has scored 53 goals at this level during his career whilst he has also chipped in with 25 assists.
As for Stockley, he managed to find the back of the net on 20 occasions in all competitions during the 2021/22 campaign and will be keen to help Charlton push forward as a club next season.