The Blues completed a move for Aubameyang for 10 million pounds to bolster their forward line while Swiss midfielder Zakaria comes in on loan with the option of a permanent deal at the end of the season.
Aubameyang joins on a two-year contract with Marcos Alonso involved in the deal, going the opposite way to Camp Nou.
The former Arsenal striker said: “Im really happy. Its an honour to be part of this team and I cant wait to start. I have some unfinished business with the Premier League so its good to be back and really exciting.”
Chelsea chairman Todd Boehly added: “Pierre-Emerick is an elite striker with a proven track record in the Premier League and his arrival strengthens our squad, giving us new attacking options.
“Denis is a talented midfielder with lots of quality and skill. He will add depth and range to our squad this season, and we are looking forward to watching him play in Chelsea blue.”
Barcelona not only added Marcos Alonso, but also full-back Hector Bellerini who joined on a free transfer from Arsenal, while Frenkie de Jong ultimately stayed. Sergino Dest moved to AC Milan on loan.
Liverpool landed Brazilian midfielder Arthur on loan from Juventus, while Manchester United’s 95 million euro move for Antony from Ajax got finalized, along with a deal to sign goalkeeper Martin Dubravka from Newcastle United to provide competition to David de Gea.
The Cottagers also signed forward Carlos Vinicius from Benfica for an undisclosed fee, with ex-Arsenal and Chelsea winger Willian signing on too.