"I'm very happy that we could finish this deal and I'm very happy to be here", Mkhitaryan told Arsenal's official website after confirmation of the blockbuster switch.
"I remember today, a conversation I had with Henry, a historic Arsenal player, who changed club for the same reason and today is my turn".
Sky Sports News showed Armenian worldwide Mkhitaryan, also 29, at a central London hotel on Saturday evening alongside agent Mino Raiola ahead of his expected move.
And manager Arsene Wenger, who last week sold Theo Walcott to Everton, is hopeful the club can now move on from the saga.
The United boss was vocal in his calls for the club's owners to compete with Manchester City for top players last month and while those public comments appeared to be risky, he was clearly pushing his case for this deal for Sanchez to be finalised.
Sanchez, 29, is set to become United's best-paid player, with his wages estimated at more than £500,000 ($695,000, 567,000 euros) a week.
GETTY Henrikh Mkhitaryan and Alexis Sanchez could be swapping clubs this month
"It really is a massive club, very powerful, and so now, when I got the opportunity to come here, I looked at the badge and my hairs just stood up on end because it's a powerful club and the biggest in England".
But McClaren believes United have struck a major blow by landing Sanchez, who has scored 80 goals in 166 appearances at Arsenal.
And Smalling believes that if United can get to within touching distance before that game at the Etihad Stadium, they will have a chance of lifting the title.
"We have tried to find the best possible solution and the best possible solution is that we lose a world class player - I don't deny that at all - but we did not lose him without getting somebody after".
That's hard so that's why I made a decision to leave him out.
'Wage parity is very important to players.
While Arsenal promise to be very busy in the final stages of the January window, United are not expected to bring in further additions.
Giroud's probably frustrated about a lack of playing time, and a move to an Auba-less Dortmund might solve that problem for him, but it doesn't solve the problem of Arsenal no longer having Olivier Giroud.
Extra cargo checks for US-Mideast flights
High-grade military explosives were sent by air cargo from Turkey as part of that plot, according to Australian law enforcement. That plot caused the TSA in September to issue stricter screening rules for cargo traveling to the USA from Turkey.