The international football player from Germany signed a contract with Arsenal that would keep him there until 2028 and cost Chelsea £65 million.
The two London clubs have been in talks for a few weeks, but the transaction is moving quickly.
After speaking with manager Mikel Arteta, Havertz previously consented to personal terms.
The forward left with a very upbeat attitude and was eager to relocate across town as a result.
Arteta put a lot of effort into the transfer and believes Havertz will be important in the coming season.
It surpasses the £50 million paid for Gabriel Jesus last summer as the biggest money Arsenal has spent on a player since the Spaniard took over in 2019.
As a player who can play anywhere along the frontline, it is unclear where the 24-year-old will slot into the starting lineup.
He might potentially replace Granit Xhaka in the left midfield position, which would strengthen an attack-oriented team even more.
Although Havertz is the first player the Emirates have signed this summer, it appears exceedingly unlikely that he will be the last.
Jurrien Timber, who has been courted by Arteta and wants to leave Ajax, is still the subject of transfer negotiations.
Declan Rice is a deal that is still in the works, with Arsenal expected to defeat Manchester City for the West Ham and England player.
Xhaka is expected to leave for Bayer Leverkusen, where Havertz came up through the ranks, while Thomas Partey could also depart.
Arsenal have always been keen to make signings as soon as possible rather than let them drag on into the latter weeks of the transfer window.
Landing Havertz is a statement signing from the north London outfit, considering they have pinched him off their Premier League rivals.
It is the second transfer of its kind in recent times, having also brought in Jorginho from Stamford Bridge in January.
Both were key players at Chelsea as they won the Champions League in 2021, where Havertz scored the winner against City in the final.
As for the Blues, the German is one of several exits expected in the coming weeks.
N’Golo Kante, Edouard Mendy and Kalidou Koulibaly have already left for Saudi Arabia and Hakim Ziyech soon.
Mateo Kovacic has gone to Manchester City and Mason Mount remains on Manchester United’s wish list, while Pierre-Emerick Aubameyang, Callum Hudson-Odoi and Ruben Loftus-Cheek are all linked with departures.