Born in La Plata, Buenos Aires Province, Rulli graduated from local Estudiantes' youth setup, being promoted to the first-team squad in 2012, being initially assigned as a backup to Justo Villar and Agustín Silva. On 8 April 2013, after profiting from Villar's departure to Nacional and Silva's injury, he played his first match as a professional, starting in a 0–1 loss at Arsenal de Sarandí. Rulli appeared in further 11 matches during the campaign, and established a record of 588 minutes without suffering a goal. He appeared in all league matches in 2013–14, overtaking Silva in the pecking order.
Real Sociedad
On 24 July 2014 Rulli was loaned to La Liga's Real Sociedad for one year from Deportivo Maldonado, which bought the player's rights a month earlier. He made his debut for the club on 28 August, starting and being replaced in the 85th minute of a 0–3 away loss against FC Krasnodar for the season's UEFA Europa League due to an ankle injury. Rulli returned to action in November, and made his debut in the main category of Spanish football on 20 December 2014, starting in a 1–1 away draw against Levante UD. On 4 January of the following year, he made several key saves which granted the Txuri-urdin a 1–0 home win against FC Barcelona. On 4 July 2015, Rulli's loan was extended for a further year. On 19 July 2016, Rulli was signed by Premier League side Manchester City for £4 million. He was shortly afterwards loaned back to Real Sociedad, before moving permanently in January 2017. On 14 August 2019, Rulli joined Ligue 1 club Montpellier on a season-long loan with the option to make the transfer permanent.
International career
On 20 March 2015, Rulli was called up to the Argentina national team for the matches against El Salvador and Ecuador, but he did not play in either fixture. In 2016, Rulli was included in the preliminary squad for Copa América Centenario but was eventually excluded. After Jorge Sampaoli took charge in May 2017, Rulli had consistently been called up to Argentina's senior squad, however had yet to secure his first cap. Under Lionel Scaloni, Rulli made his first team debut against Guatemala on 8 September 2018.November 20, played at the start of a friendly match against Mexico, when Argentina won 2-0 and took Copa Adidas 2018
