The 20-year-old is expected to join Arsene Wenger's side in July when the transfer window opens.
It has been quite a few years for the former French youth international who suffered a major leg injury in 2010 and was unsure if he would continue playing.
Speaking to France Football he said: "I wanted to stop. I told myself it was useless to go on and to imperil my health.
"I could not run any longer. I had too much pain, the doctors didn't know what to do. But, one day I went for a jog and step by step I made my way back."
French Ligue 1 side Lille were also linked with Sanogo and he says that it was a straight fight between them and Arsenal for his signature.
Sanogo added: "I told my agent the choice would be made between these two clubs. Lille's coach Rudi Garcia called me all the time. I hesitated a lot.
"Gilles Grimandi [Arsenal scout] came to see me from time to time at Auxerre too. One day he called me for a meeting in a Paris hotel and Arsene Wenger was there. I was very impressed."
And it was during that meeting that Sanogo made his decision to join the north London club.
"Wenger told me I would get opportunities and reassured me about my injury. He told me he had followed me for years. That meeting was very important and today I am an Arsenal player," said Sanogo.
"It will be an amazing adventure. I am just eager to start in one of the best leagues in the world. It is a dream that has come true."