The United States Lighthouse Board erected a beacon on the northwest side of the island in 1928, followed by the addition of a second beacon on the southwest corner in 1934. The United States Coast Guard took over servicing, and replaced the northwest tower with a steel tower, solar-powered, in 1980.

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As early as 1853 government officers made note of the potential of Santa Barbara Island for lighthouse purposes. United States Coast Survey topographers noted the adaptability and location advantage of the island in the Southern California Bight, an area used heavily by maritime traffic since before the Gold Rush. Nonetheless, it would take 75 years to get a navigational aid built on Santa Barbara Island.

For unknown reasons the Bureau of Lighthouses ignored Santa Barbara Island for the last half of the 19th century. Only at the urging of the Lighthouse Board in 1903 did the government take action. An Executive Order by President Theodore Roosevelt reserved Santa Barbara Island for lighthouse purposes on August 24, 1905: "It is hereby ordered that an unsurveyed Island, known as Santa Barbara Island, situated in the Pacific Ocean in approximate sections 1, 2, 12 and 13, township 8 south, range 21 west, San Bernardino meridian, containing approximately 638.72 acres, be and it is hereby reserved for light-house purposes."

On July 27, 1928, the Bureau of Lighthouses authorized an automatic light on the northerly point of the island "for the protection of inter-island navigation in general and particularly for the protection of the Hawaiian Island and trans-Pacific traffic, which follows a course passing six miles to the northward of the island."

By this time, the Los Angeles Harbor had surpassed San Francisco in tonnage and became the principal terminus for trade on the whole west coast. The Commissioner of Lighthouses approved a light for Santa Barbara Island in letters of January and March of 1928, and an allotment was made by the Bureau in connection with funds for additional aids to navigation on Anacapa Island.

The light would be a 375 mm AGA acetylene lantern equipped with a K130 flasher, S20 sunvalve, and one-foot burner (390 candlepower) adjusted to show a flashing one second light every six seconds; it would be powered by twelve A-25 accumulators, or tanks of acetylene gas. Structures included the light tower with an accumulator house, built at San Francisco's Yerba Buena Island and disassembled for shipment. The equipment and labor would cost $2,286.00. The white wooden pyramid was constructed on the island by the district carpenter; the light installed by the "mechanician" and assisted by the crew of the lighthouse tender anchored off shore. The tower was located 195 feet above the water and appeared on the 1929 Light List as unwatched. The location given was the northeasterly point of the island, 33 degrees 29".3' latitude north and 119 degrees 01".8' longitude west. A new trail from the landing cove offered access by foot and handcart.

In 1934, a second light tower went up on the south end of the island, westerly side, located 486 feet above the water and visible for twelve miles. The light, a 480 candlepower unwatched beacon on a steel skeleton tower, was on a ten second cycle, two seconds of flash. Workers built a trail between the landing and the southern light.

At the outbreak of World War II, the military ordered both lights temporarily extinguished. They were relighted in 1943 when the immediate threat to Los Angeles Harbor was felt to be over. During the war the Navy took over responsibility for U. S. Coast Guard activities, including aids to navigation, and instituted a program of timed blackouts of coastal lights in case of enemy attack. The Navy placed additional navigational buoys and developed a blackout system called ANRAC during the blackout in 1942, which was able to control acetylene and electric lights on buoys or fixed structures. The control station, located on the mainland, could control the remote lights now equipped with radio receivers and relays.

However, the Coastal Lookout observers evidently operated the Santa Barbara Island lights on site; the Observer in Charge at the island in December 1944 wrote to his superior telling of a faulty switch resulting in a temporary failure of the light. In June of 1945 the Commandant of the 11th Naval District advised that both island lights would be replaced by acetylene or automatic lights, would be maintained by the Coast Guard, and would no longer be subject to blackouts. The ANRAC system was dismantled in September of 1945.

After the war the Coast Guard maintained the lights on a regular basis. The major responsibility was replacing the accumulators, gas cylinders weighing about 150 pounds each. Coast Guardsmen visited the island on tender ships such as the Diligence, hauling supplies on carts and making any repairs as necessary. A tramway left by the Navy from its wartime occupation of the island was maintained and used by the Coast Guard to haul supplies up the steep hill to the trails leading to the lights.

Instead of the jeep they had requested after the war, Coast Guard men had hoisted a stripped down Model A Ford up the tramway for use hauling the twelve heavy acetylene tanks to each light twice a year. Because the soft island soil provided poor traction, the men "welded tractor lugs of heavy angle iron to the bare rims," thereby churning up the earth to get to their destinations.

On July 10, 1959, a fire denuded over two-thirds of the island and destroyed the south light tower. Permanent discontinuance was published on October 16, 1959. The northeasterly light remained operational.

By 1979 the pyramidal wooden Santa Barbara Island Light structure was in poor condition. The historic resource study published that year noted that it was "critically in need of paint and general repair. The door is unlocked, but jammed, and the fittings are rusted and need replacement." As the oldest structure remaining on the island, the light "presents a poor and deteriorating appearance." The light tower was subsequently removed, replaced by a modern steel tower with a solar-powered beacon in 1980.