The Spanish midfielder, 25, has moved on loan until the rest of the season with an option to make it permanent in the summer.
Barca actually confirmed the deal on their website yesterday but were forced to remove their announcement after it was revealed the finer details were yet to be finalised.
But that has now been done and Arsenal have finally signed a player they have been tracking since the very beginning of the January transfer window.
Suarez joins up with Arsenal manager Unai Emery for the second time in his career having worked under him while the pair were at Sevilla.
Emery said he was delighted to finally get his man and believes his versatility will be a huge boost to the squad.
“We are very happy that Denis Suarez is joining us,” he said.
“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 said it was a dream come true to join a club he supported as a boy and is looking to follow in the footsteps of some of greatest players in the club’s history.
“One thing no one knows about me is that when I was little and I used to watch the Premier League on the TV, Arsenal were a team that really inspired me,” he said.
“I used to watch (Dennis) Bergkamp and (Thierry) Henry – they’re both legends of the club and hopefully we can follow in their footsteps.”
Suarez becomes Arsenal’s first signing of the winter window and it remains to be seen heather they will do any more business before the deadline at 11pm today.
They remain keen on Inter Milan’s Ivan Persicv but time is running out as the two teams are nowhere near agreeing on the terms of the deal.
Perisic wants to move and handed in a transfer request at the weekend but Arsenal can only afford a loan deal with an option to buy.
Inter are understood to be holding out for a permanent transfer or a guarantee that Arsenal will sign him in the summer at the very least.
The Gunners have also been linked with a shock late move for Everton midfielder Idrissa Gueye.
Gueye is wanted by Paris Saint-Germain, who submitted a £21million offer last week.
That offer was rejected because it falls below there £40m valuation but Gueye then wrote to club chiefs and begged them to let him leave.
Arsenal are said to be willing to pay the asking price if they can take him now and pay the fee in the summer.
The Gunners are also still tracking PSG midfielder Christopher Nkunku but that could be complicated if they do pursue a move for Gueye.
PSG are said to be willing to let Nkunku go but only if they can sign Gueye.