Arsene Wenger claims the £30m signing of Alexis Sanchez from Barcelona has "excited" everybody inside Arsenal.
Sanchez was confirmed as an Arsenal player after travelling to London to undertake a medical and sign a four-year contract worth around £130,000 a week.
The deal makes forward Sanchez the second most expensive player in Arsenal's history behind Mesut Ozil, who joined for £42.5m last year.
His signing should be quickly followed by the confirmation of right-back Mathieu Debuchy's £11m move to the Emirates.
Manager Wenger made his first move for Sanchez while away in Brazil at the World Cup where the forward starred for Chile, scoring two goals in four appearances.
"As many people have seen during the World Cup this summer, Alexis is a fantastic footballer and we are delighted that he is joining us at Arsenal," said Wenger.
"Alexis will add power, creativity and much quality to our squad and we are all looking forward to him joining up with us in a few weeks.
"He has consistently produced top-quality performances at the highest level for a number of seasons now and we are all excited to see him integrate into the Arsenal squad."
Sanchez made a total of 88 appearances for Barca, scoring 39 goals during three seasons in Spain.
Liverpool wanted to take the 25-year-old as part of Barca's deal to sign Luis Suarez, while Juventus were also keen on the striker.
But the lure of London and playing for Wenger swayed Sanchez towards the Emirates and he will meet up with his new Arsenal team-mates at the end of this month, having made it to the last 16 of the World Cup with Chile.
Sanchez is expected to make his first Arsenal appearance in the Emirates Cup, which takes place on August 2-3.
"I'm so happy to be joining Arsenal, a club which has a great manager, a fantastic squad of players, huge support around the world and a great stadium in London," said Sanchez.
"I'm looking forward to playing for Arsenal in the Premier League and Champions League. I will give my best to Arsenal and want to make all the supporters happy."
Sanchez can play anywhere across the front three and will add goals and pace to Wenger's squad.
He has made 71 appearances for Chile, scoring 24 goals, starting his club career with Cobreloa, based in Calama in north Chile, where he spent a season before moving to Santiago-based Colo-Colo, where he won the Chilean Primera Division in 2007.
After impressive performances in Chile between 2005 and 2007, Sanchez went on loan to Argentine side River Plate, where he added the Argentinian Primera Division to his honours.
Following his success in South America, Sanchez moved to Serie A side Udinese in 2008, where he spent three seasons, scoring 20 goals from 95 appearances.
His displays in Italy prompted Manchester City to launch a huge bid to try to sign Sanchez in 2011, but Barcelona made a rival offer and the player decided to move to the Nou Camp.
The Gunners continue to work on bringing in other reinforcements to mount a long-overdue sustained assault on the Barclays Premier League title, having been clear at the top in January only to fade away and finish fourth.
While Debuchy will represent a Premier League-ready replacement for Bacary Sagna, who left on a free transfer to Manchester City, Wenger also has his mind on further additions.
QPR forward Loic Remy, rated at around £8million, is a potential target, having spent last season on loan at Newcastle, along with Bayer Leverkusen midfielder Lars Bender. Reports have also linked Arsenal with Real Madrid's Germany midfielder Sami Khedira