Besides AC Milan, Andrea Conti has only played for Atalanta. He has been raised into their famous footaball academy.
Conti was born and raised in Lecco, Lombardy. In 2002, he had a successful trial at A.C. Milan yet refused to join the team due to his dislike of the club’s youth training center in Linate area of the city, as well as its far-from-home location. He also had an offer from the club’s cross-city rivals, Inter Milan, yet eventually joined Atalanta’s youth academy where he would play together with Mattia Caldara and Roberto Gagliardini for over a decade.
In July 2013, Conti was loaned to Lega Pro side Perugia. He made his professional debut on 4 August 2013, starting in a 0–1 Coppa Italia home loss against Savona. His first league appearance occurred later that month, a 2–2 away draw against Nocerina. Conti made 16 league appearances, helping his team achieve promotion to Serie B.
On 10 July 2014, Conti moved to a fellow second-tier team Virtus Lanciano, in a season-long loan deal. Conti made 24 league appearances while his team finished 14th out of 22. In the summer of 2015, he returned to Atalanta and was included in the first team squad for the upcoming Serie A season.
On 30 September 2015, Conti signed a new contract with Atalanta until July 2019. He made his debut for the club on 2 December, in a 1–3 loss against Udinese in Coppa Italia. Conti made his debut in Serie A on 6 January 2016, in a 1–2 loss against the same opponent. His first goal in the competition occurred on 3 February, in a 2–1 win against Verona.
Conti managed to score 8 goals in 33 appearances during the 2016–17 Serie A season, setting a personal record for scoring. His main playing position was a right wing-back in a 3–4–3 formation.