Lanzini fought his way back to fitness and was a reliable squad player for the next 5 seasons, culminating in winning the 2023 UEFA Europa Conference League.

The knee injury suffered in 2018 meant he missed the opportunity to feature at the 2018 FIFA World Cup, and he has made only one subsequent appearance for the national team in 2019.

[10] Lanzini made his informal debut in a friendly match against Central Norte, a 3–0 victory, coming on as a second-half substitute for Ariel Ortega.

[11] Lanzini then played another friendly match against Juventud Antoniana, where his performance earned good reception from press and fans alike.

After his debut, Cappa excluded him in the match against Huracán, but he replaced the suspended Ariel Ortega in the next game against Independiente where he assisted Rogelio Funes Mori's goal for the 3–2 victory.

[28] Almeyda was fired and the club's most successful coach to that date, ex-Inter Milan player Ramón Díaz, was appointed as team manager.

[36] He remained one of the team's strongest players in the Torneo Inicial 2013 and the international Copa Sudamericana 2013, but overall River Plate were inconsistent and did not win any trophies.

[38] On 6 August 2014, prior to the beginning of the 2014 Torneo de Transición Championship and Copa Sudamericana 2014, Lanzini transferred to the Al Jazira Club in the UAE Pro-League for $6,000,000 four-year deal, with a salary amounting to $12,000,000 in 3 years.

[5] On 22 July 2015, Lanzini signed for Premier League side West Ham United on a season-long loan, with an option to make the move permanent.

[40][41] He made his debut on 6 August in the UEFA Europa League third qualifying round away to Astra Giurgiu, starting the match and scoring in the third minute, however the Hammers lost 2–1 (4–3 on aggregate) and were eliminated.

[54] After being sidelined due to injury since May 2018, Lanzini made his first appearance of the season on 22 February 2019, coming on as a 76th-minute substitute for Felipe Anderson in a 3–1 home win against Fulham.

[46] Lanzini made his first appearance of the season on 10 August 2019 in West Ham's opening game against 2018–19 Premier League Champions, Manchester City, resulting in a 5–0 loss.

[60] Through Lanzini's equaliser, West Ham became the first team in Premier League history to avoid defeat, having been losing by three or more goals, as late in the game as the 81st minute.

[63] He returned to the pitch later that month, coming in for Matías Kranevitter during the second half at Argentinos Juniors' Diego Armando Maradona stadium.

[65] He withdrew from the squad in July 2016 following a knee injury sustained while training in Miami, Florida, returning to London for treatment with West Ham United.

On 23 March 2018 he played a friendly match against Italy at the Ethiad Stadium in Manchester and scored his first international goal as Argentina secured a 2–0 victory.

[67] On 21 May 2018 he was named in Argentina's final 23-man squad for the 2018 FIFA World Cup in Russia,[68] and started in the 4–0 friendly win against Haiti on 29 May in Buenos Aires, playing an hour before being substituted by Maximiliano Meza.

[69] On 8 June 2018, Lanzini was ruled out of the World Cup after suffering a ruptured anterior knee ligament injury during a training session.