According to the 2002 census of the National Statistics Institute, Talcahuano spans an area of 145.8 km2 (56 sq mi) and has 250,348 inhabitants (121,778 men and 128,570 women). Of these, 248,964 (99.4%) lived in urban areas and 1,384 (0.6%) in rural areas. The population grew by 59.9% (93,766 persons) between the 1992 and 2002 censuses. With a population density of 1,873 inhabitants per square kilometre, it is the seventh most populated city of the country.
The official foundation date of Talcahuano is November 5, 1764 when Antonio Guill y Gonzaga declared an official port. However, Talcahuano began to appear in history books as early as 1544 when Genoese captain Juan Bautista Pastene discovered the mouth of the Biobío river while exploring the coast in his ships “San Pedro” and “Santiaguillo”. In 1601 Alonso de Ribera built Fort Talcahueno to defend remaining Spanish settlements near Concepción.
The city is named after an Araucanian chief, Talcahueñu, who inhabited the region at the arrival of the Spanish. In Mapudungun, the language of the indigenous Mapuches, Talcahuano means “Thundering Sky”.
The port was well known to American whaleships of the 19th century. They often put in for fresh water, food, and various forms of entertainment for the crews.
The 2010 tsunami carried this pleasure boat ashore.
On February 27, 2010 Talcahuano was devastated by the 8.8 magnitude 2010 Chile earthquake and its subsequent tsunami. These back-to-back disasters left 80% of the city's residents homeless.  The tsunami is estimated to have been more than 7.5 feet high. After a week, there are only 20 reported deaths, and 18 missing. The city government estimates that it will take 10 years to recover from the quake and tsunami. The local government has been turning away tent aid, as they want to make permanent shelters rather than have permanent tent camps.
Talcahuano contains Chile's main naval base which is home of the historical relic, the Huáscar, a Peruvian ironclad ship (British-made), which was captured in 1879 during the War of the Pacific. It is also the base of the Chilean submarine fleet and the ASMAR shipyard.
Within the electoral divisions of Chile, Talcahuano is represented in the Chamber of Deputies by Jorge Ulloa (UDI) and Cristián Campos (PDC) as part of the 43rd electoral district, (together with Hualpén). The commune is represented in the Senate by Alejandro Navarro Brain (MAS) and Hosain Sabag Castillo (PDC) as part of the 12th senatorial constituency (Biobío-Cordillera).