Velasco was built by the Thames Ironworks & Shipbuilding & Engineering Co. Ltd. at Leamouth, London in the United Kingdom, as the lead ship of a new class of eight Spanish unprotected cruisers. Her keel was laid in 1881. She had one rather tall funnel. She had an iron hull and was rigged as a barque. She and the second ship of the class,, also built in the United Kingdom, were differently armed from and slightly faster than the final six ships of the class, all of which were built in Spain.
In 1891 the cruiser was sent on a patrol to Northern Luzon and the surrounding islands to watch out for potentially suspicious activities of Japanese merchant shipping.[1]
When the Spanish–American War began in April 1898, Velasco was anchored in Manila Bay off the Cavite Peninsula as part of Rear Admiral Patricio Montojo y Pasaron's Pacific Squadron. In the Battle of Manila Bay, she was still anchored there when the U.S. Navy's Asiatic Squadron attacked Montojo's squadron on 1 May 1898. Her boilers were ashore being repaired. All her guns were apparently removed to the Caballo Island Battery. She did not participate in the battle although ended up sunk.