For a reported fee of £30 million after signing a four-year contract with the option of an additional two, the defender joined the Red Devils in June 2016 to become Jose Mourinho's first signing.
Since moving to the Old Trafford, the 24-year-old has made 67 appearances across all competitions and played a key role as United won the 2017 Europa League.
And the Cote d'Ivoire international has explained how the transfer from the Spanish side materialised.
“I was with my mum in the lounge and I told her I was going to sign for United,” Eric said in a documentary entitled l’Elephant d’Afrique as per club website.
“The family came and we talked and everyone was delighted. That day was one big happy time.
”Then I had to get on the flight to come and finalise all the arrangements in England. I had to undergo medical tests and sign here in Manchester.“
Bailly who started his career from his home country moved to Europe at the age of 17 after joining Espanyol's youth set-up.
“When I was in the Ivory Coast training centre, we had a small staff, a different system from Europe but they taught us a lot and it was there I realised that with hard work I could make it,” Bailly continued.
“Why not become a professional player in Europe? I believed in myself and continued to grow, to pray and that’s how I became a professional player in Europe.”
Herve Renard, former coach of the Cote d'Ivoire national team handed Bailly his international debut in a friendly game against Nigeria in January 2015 at the age of 20.
“In Africa, sometimes the name is more important than the talent but I don’t care,” Renard said in the documentary.
“[In Eric] I saw someone very young with a lot of skill and very fast for a defender, which is what coaches like. I didn’t have any doubts about him.
“To be honest with you, after four or five days [of training], I knew already he was in the first XI.”