The Federal State of the Visayas, a short-lived revolutionary state composed of the Provisional Government of the District of Visayas ( Panay), the Cantonal Government of Bohol, the Cantonal Government of Negros, and the island of Cebu, was later established, and the City of Iloilo became its capital. Iloilo was the last capital of the Spanish Empire in Asia and the Pacific before the Philippines was ceded to the United States in 1898 through the Treaty of Paris. Iloilo was also more popularly known as the Queen City of the South, being second to the most important and primate city in the Philippines, after Manila, at the turn of the 20th century in terms of economy, with foreign and local commercial establishments lining the whole stretch of Calle Real (Iloilo's Escolta and old business district), an agricultural experimental station established at La Paz in 1888, a school of arts and trades which opened in 1891, and a telephone network system operating in the metropolis in 1894. Iloilo was the second city in the country to have such a byname, after the City of Manila in the Spanish colonial era Philippines. It was an inscription in the Coat of Arms from the Royal Decree of 1896, for the city's loyalty to the Spanish crown during the Philippine Revolution, and it remained inscribed on the city's official seal until the present. The honorific royal title, La Muy Leal y Noble Ciudad or Most Loyal and Noble City, was acquired by the city on March 1, 1898, given by Queen Regent Maria Christina.

604 of August 22, 1940, issued by President Manuel L. 158, by consolidating the existing City of Iloilo with the towns of Arevalo, Mandurriao, Molo, and La Paz, while the City of Jaro was officially annexed on January 7, 1941, through the virtue of Commonwealth Act No. Iloilo was established as a city three times: first, on October 5, 1889, through a royal Spanish decree issued by the Queen Regent of Spain, Maria Christina, and became one of the few Royal Spanish Cities in the Philippines in Spanish Asia second, on February 7, 1890, through a legal declaration by virtue of the Becerra Law of 1889, establishing the city government of Iloilo, and became the first legal city in the Philippines and third, on July 16, 1937, formally inaugurated on August 25, 1937, as a chartered city, through the virtue of Commonwealth Act No. It was the second Spanish colonial center after Cebu in the Philippine Islands. The first Spanish settlement in Iloilo was founded in 1566, when the Spaniards established a colony area between the towns of Ogtong (present day Oton) and La Villa Rica de Arevalo (present day city district). The district of Lapuz, a former part of La Paz, was declared a separate district in 2008. Iloilo City is a conglomeration of former towns, which are now the geographical or administrative districts consisting of: Villa de Arevalo, Iloilo City Proper, Jaro (an independent city before), La Paz, Mandurriao, and Molo. For the metropolitan area, the total population is 1,007,945 people.

According to the 2020 census, Iloilo City has a population of 457,626 people. In addition, it is the center of the Iloilo–Guimaras Metropolitan Area, as well as the regional center and primate city of the Western Visayas region. It is the capital city of the province of Iloilo, where it is geographically situated and grouped under the Philippine Statistics Authority, but remains politically independent in terms of government and administration. Iloilo City, officially known as the City of Iloilo ( Hiligaynon: Siyudad/Dakbanwa sang Iloilo Tagalog: Lungsod ng Iloilo), is a 1st class highly urbanized city in the Western Visayas region of the Philippines on the island of Panay. Nuestra Señora de la Candelaria (Our Lady of the Candles) – Official Roman Catholic Patron of Western Visayas and Romblon.

Prosync labor rate