The 30-year-old is expected to be announced next month as the next signing in a defensive overhaul at the Emirates under new manager Unai Emery, in a deal reportedly worth up to £16m from Borussia Dortmund.
Shedding light on the move which will see Sokratis switch the Bundesliga for the Premier League, Charalambos let slip that the Gunners were not the only club interested in securing the centre back's signature ahead of next season.
"United had a very good relationship with Dortmund, the teams talked a lot, but Socrates chose to go to Arsenal," Charalambos Papastathopoulos told Contra Gr 24/7 radio.
"He is happy, he is in England at the moment, and tomorrow everything will be done, the formal, everything will go well, he is happy, he is changing, I think he is going to a higher level.
"English league is the highest in the world, the most competitive and I believe there will go well."
Despite the Greece international being set to put pen to paper on a three-year deal with the option of a fourth at the Emirates, the 30-year-old will still have to wait until July to have his move made official as Dortmund want to wait until their current financial year finishes.
The German club's sports director, Michael Zorc confirmed as much earlier this week: “It seems that it’s going to happen. It is true. But it is not entirely in place yet.”
Sokratis is likely to partner Shkodran Mustafi or Laurent Koscielny and will add further experience to Arsenal's back line following the recent signings of Stephan Lichtsteiner and Bernd Leno.