In 1918, the club obtained recognition as a national champion when he beat the team of the nascent Peruvian Football League, which he defeated by 2 to 1.

Very fast the club conquer the affection of the Callao leaving indelible testimonies through many generations who won the triumphs that helped the contact and development of the town.

The first National Olympic was carried out by the year 1917, and in the Championship was imposed as unbeaten, obtaining as prize a great shield that was exhibited in its old localities of the (Today Av.

In 1947, after a great campaign and under the presidency of Mario Chiabra, the Atlético Chalaco, be consecrated again National Champion, they participated in said championship under the direction of the coach "Patuto" Arana the following players: Humberto Becerra, Eliseo Moral, Rene Rosasco, Juan Lecca, Félix Mina, "Perejil" Reynaldo Luna, Ernesto "Chicha" Morales, Guillermo Aguilar, Luis Rodriguez, Domingo Raffo (captain), Carlos Torres, Juan "Cartucho" Castillo.

In the 1950s the team earned the nickname 'Ballet Porteño' by its good play emphasizing the Paraguayan goalkeeper Adolfo Riquelme, Andrés Bedoya, Sabino Bártoli, Luis Portanova, Jacinto Villalba, Germán Colunga, Rene Rosasco, Felix Mina, Santiago Armandola, Gualberto Bianco, Antonio Aguiar and Luis López.

After an intense fight by recovering its seat of honor, in 1971 was champion in the League of the Callao and upon winning the home run of the Interligas to the teams of Lima elevates to the Second Division.

Of that staff they emphasized Fernando Apolinario, Augusto Prado, Oscar Arizaga, Victor Benavides, Javier Chirinos and Alberto Castillo.

In recent years the León Porteño assembled good teams and advanced in the Peru Cup, but failed to surpass the Regional phase of the versions 2000, 2002, 2005 and 2007.

In the 2008 it is elected president Alex Kouri, doing an important investment to achieve the title of the Peru Cup and the ascent to First Division, nevertheless again only he would arrive to the Regional Phase where would be eliminated by the Union Supe that defeated it in both matches.

Through the ranks of "León Porteño", great players and scorers passed that nurtured and formed the character of Peruvian football, such as Telmo Carbajo, Claudio Martínez Bodero, Alfonso Saldarriaga, Enrique Salas, Antonio Maquilón, Manuel Puente, José Arana, Humberto Crescimbeni, René Rosasco, Domingo Raffo, Félix Mina, Carlos Torres, Andrés Bedoya, Óscar Arizaga, Augusto Prado.