Cod's keel was laid down on July 21, 1942, at the Electric Boat Company in Groton, Connecticut, but her heart was built in Cleveland. The submarine's four main Cleveland Model 16-248 V16 diesel engines and one auxiliary diesel engine were manufactured by General Motors' Cleveland Diesel Engine Division on the city's west side. She was launched on March 21, 1943, and commissioned three months later on June 21, under Commander James C. Dempsey - an officer who had already won fame for sinking the first Japanese destroyer lost in World War II. From the start, Cod was a warship with a pedigree, built by two American cities and commanded by a proven submarine hunter.

Cod completed seven war patrols across the Pacific, every one classified as successful. She ranged from the South China Sea to the waters off Luzon, from the East China Sea to the Gulf of Siam. Her third patrol was among the most aggressive: on May 10, 1944, she attacked a heavily escorted convoy of 32 ships, sinking the destroyer Karukaya and the cargo vessel Shohei Maru before depth charges drove her deep. On her fifth patrol, she sank the 6,886-ton Tatsushiro Maru, then shadowed a large convoy for an additional day after expending all her torpedoes, reporting its position so others could attack. By war's end, Cod was credited with sinking more than 12 enemy vessels totaling over 37,000 tons and damaging another 36,000 tons of shipping. She earned seven battle stars.

Cod's closest brush with catastrophe came on April 26, 1945, during her sixth patrol in the East China Sea. A fire erupted in the aft torpedo room - one of the most dangerous emergencies possible aboard a submarine loaded with live warheads. The crew fought the blaze and manually launched a torpedo already in its tube before the fire could detonate it. During the effort to free the torpedo room hatch, two sailors - QM2c Lawrence E. Foley and S1c Andrew G. Johnson - were washed overboard. Foley was recovered the next morning, but Johnson drowned during the night. He was Cod's only fatality across all seven war patrols - a remarkable record for a submarine that spent two years in combat.

On July 9 and 10, 1945, during her seventh and final patrol in the Gulf of Siam, Cod came upon the Dutch submarine O-19, grounded on Ladd Reef and unable to free herself. Cod took the entire Dutch crew aboard, then destroyed the O-19 to prevent it from falling into enemy hands. It was the only international submarine-to-submarine rescue ever performed. After returning the Dutch sailors to Subic Bay, Cod spent the rest of July making 20 gunfire attacks on the junks, sampans, and barges still supplying Japanese forces at Singapore, sinking 23 vessels. On August 1, an enemy plane strafed Cod, forcing her to dive and leaving a boarding party stranded - the men were rescued two days later. When Cod reached Fremantle on August 13, the crew of the O-19 had organized a celebration. During the party, both crews learned the war was over.

After postwar mothballing and Cold War NATO exercises, Cod was towed through the St. Lawrence Seaway to Cleveland in 1959. In 1976, a group of Cleveland residents formed a committee to preserve her, and the Navy transferred guardianship. She opened for public tours on May 1, 1976, and in 1986 was designated a National Historic Landmark. What makes Cod unique among surviving World War II submarines is her integrity: she is the only one that has never had stairways or access doors cut into her pressure hull for visitor convenience. Her 5-inch deck gun, Mark IV Torpedo Data Computer, SJ-5 radar, sound-powered telephones, and all five diesel engines have been restored to working condition. In 2021, Cod made her first voyage in 58 years, towed to Erie, Pennsylvania, for a $1.1 million hull restoration. She returned to her Cleveland berth on August 18, 2021 - the same spot she has occupied since 1959.