Denis Suarez has completed his loan move to Arsenal after extending his contract at Barcelona through to 2021.
Despite penning fresh terms at Camp Nou, the deal which has taken the 25-year-old to Emirates Stadium includes the option for Gunners to push through a permanent transfer in the summer.
The Arsenal boss has previously worked with the Spain international at Sevilla.
It appeared at one stage as though his efforts to put a reunion in place would come to nothing, with talks breaking down.
Goal, however, confirmed on Tuesday that a breakthrough had been reached and a switch was back on.
Barca then inadvertently announced the deal on their official website, before hastily deleting the article in question.
Everything is now official, with Suarez linking up with the Gunners on an initial agreement through to the end of the 2018-19 campaign.
Emery told Arsenal's website on bringing in a familiar face: “We are very happy that Denis Suarez is joining us.
"He is a player we know well and I have worked with him at Sevilla. He brings us quality and options in many different attacking positions, so he’ll be able to help the team.”
Suarez has already said his goodbyes to those at Camp Nou, with an emotional message posted on social media prior to the announcement of his departure.
He said: “You’re a group of amazing people! Thank you for everything, see you soon. Good luck and Força Barça.”
Suarez has been brought in by Arsenal to compete for playing time in attacking midfielder berths with Alex Iwobi and Henrikh Mkhitaryan, who is currently sidelined with a foot injury.
He arrives in north London having made a total of 71 appearances for Barca since re-joining the club in 2016, but having been used sparingly this term.
Suarez has just two La Liga outings to his name this season, to go along with six appearances combined in the Champions League and Copa del Rey.
In his time with the Blaugrana, Suarez scored eight goals and won five trophies: one La Liga, two Copas del Rey and two Spanish Super Cups.