The 25-year-old, who impressed as Colombia reached the quarter-finals of the World Cup in Brazil, has moved to the Emirates Stadium for an undisclosed fee.
Gunners manager Arsene Wenger told Arsenal's official website: " David Ospina is an excellent goalkeeper, with good experience and a proven record of performing with Nice and Colombia
"He will add strength to our squad and we are very pleased that he will be joining us."
The keeper is expected to make his first appearance for Arsenal during the Emirates Cup friendly tournament, which takes place in north London next weekend
Ospina made 189 Ligue 1 appearances over six years with Nice having joined the south coast club from Colombian club Atletico Nacional in 2008
He made his senior debut for Atletico aged just 17 and has been a full Colombia international since 2007, making his first start for Los Cafeteros in a 2010 World Cup qualification match against Bolivia
At Arsenal he will provide competition for first-choice keeper Wojciech Szczesny while helping to fill the gap left by the departed Lukasz Fabianski, who has joined Swansea
Nice coach Claude Puel on Saturday night confirmed Ospina's move to London had been ratified and told Gunners fans they could expect some "quality" displays from the new signing
Speaking to Sky Sports News after Nice's friendly defeat to Brentford, Puel said: "It's confirmed, yes
"It's a good affair for Arsenal because he's a very good player
You will see next season the quality of this player.
"It's fantastic for him
It's important for him to try another league, another club and Arsenal is a fantastic club for him.
"David Ospina can take the goalkeeping position at Arsenal because his qualities are very strong and..
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You saw in the World Cup how important a goalkeeper he is.
"For me, David can impose his quality, he's a goalkeeper who is very good with the feet, with his arms, he knows football and he's a very, very good player."
Another player expected to move to the Emirates Stadium is Southampton defender Calum Chambers, with a £16million deal understood to be under discussion
Source : PA
Source: PA