The 22-year-old Frenchman spent the past two seasons with DAMS in FR3.5, though he had to settle for two victories - including the 2014 Monaco Grand Prix support race - while team-mates Kevin Magnussen and Carlos Sainz Jr won the titles.
Nato tested Arden's GP2 car in Abu Dhabi last winter, when he also had runs with Racing Engineering and Russian Time.
"I am delighted to join such an experienced and successful team for my debut in GP2," said Nato,
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"The Abu Dhabi tests went well and I had a great feeling with the team.
"Although I am a rookie, I aim to achieve a strong performance in 2015."
Arden team boss Garry Horner said Nato had made a good impression on him in FR3.5, where the squad also races.
"We have had the opportunity to observe him closely throughout his year in the World Series championship and feel he is ready for the step into GP2," said Horner.
Though a long-time GP2 frontrunner with drivers including Heikki Kovalainen, Bruno Senna and Sebastien Buemi, Arden has not won in the series since it took four victories with Luiz Razia in 2012. Nato is its GP2 first signing for this year.
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