Due to heavy loss rates of US aircraft (commencing with Operation Rolling Thunder 1965), studies were conducted on ways of alleviating those air losses while at the same time delivering the ordnance payloads required by the escalation of the war. On 31 May 1967 the Secretary of Defense authorized a study aimed at determining what would be required to get New Jersey reactivated in her present condition, and when the results of the submitted study proved favorable toward the reactivation the Secretary of Defense took action. In August 1967 the Secretary of Defense made the decision to recommission a battleship "for employment in the Pacific Fleet to augment the naval gunfire support force in Southeast Asia". New Jersey was selected for this task because she was in better material condition than her sisters, having received an extensive overhaul prior to decommissioning. Upon her reactivation she underwent a period of modernization during which the 20 mm and 40 mm anti-aircraft guns on the battleship were removed, and she received improved electronic warfare systems and improvements to her radar. Armed as such New Jersey was formally recommissioned 6 April 1968 at the Philadelphia Naval Yard, Captain Edward Snyder in command.

New Jersey, then the world's only active battleship, departed Philadelphia 16 May, calling at Norfolk and transiting the Panama Canal 4 June before arriving at her new home port of Long Beach, California, 11 June. Further training off Southern California followed. On 24 July New Jersey received 16 inch shells and powder tanks from Mount Katmi by conventional highline transfer and by helicopter lift, the first time heavy battleship ammunition had been transferred by helicopter at sea.

Departing Long Beach 2 September, New Jersey touched at Pearl Harbor and Subic Bay before sailing 25 September for her first tour on the gun line along the Vietnamese coast. Near the 17th parallel on 30 September, the battleship fired her first shots in battle in over sixteen years, expending a total of 29 sixteen inch rounds against Communist targets in and near the DMZ at the 17th parallel). New Jersey took up station off Tiger Island 1 October and fired at targets north of the DMZ before moving south that afternoon to engage Viet Cong targets. She accounted for six bunkers, a supply truck and an anti-aircraft site that day; additionally, she helped rescue the crew of a Marine spotting plane forced down at sea by anti-aircraft fire. On 3 October New Jersey fired on targets south of Tiger Island, and on 4 October the battleship fired on a Communist troop concentration and destroyed several bunkers. On the evening of 7 October New Jersey received word that a number of waterborne logistics craft were moving south near the mouth of the Song Giang River. New Jersey responded by closing on the formation, and succeeded in sinking eleven of the craft before they could beach. On 11 October New Jersey engaged a coastal installation with her guns; however, she shifted her fire when a recon plane spotting for the battleship reported an enemy truck concentration north of Nha Ky. New Jersey gunners quickly retrained the battleship's big guns and managed to inflict heavy damage on six of the vehicles.

Early on the morning of 12 October New Jersey trained her guns in anticipation of shelling the heavily fortified and well protected Vinh caves. For the next three days New Jersey pounded the area with her 16 in shells in an effort to eliminate the Viet Cong presence in the region. Aided by spotter aircraft from the aircraft carrier America, New Jersey engaged enemy targets, setting several enemy positions on fire and sealing one cave. On 14 October New Jersey shifted her gunfire to the coastal artillery sites on Hon Matt Island, destroying one battery on the island.
On 16 October New Jersey took up station in support of the US 3rd Marine Division. Using both the 16 in and 5 in guns New Jersey engaged and destroyed 13 structures and an artillery site, in the process halting an enemy platoon moving through the DMZ. New Jersey continued to lend firepower support on the 17th until departing to lend her gunfire to the First Field Force. Foul weather prevented spotter aircraft from flying until 20 October; however, New Jersey quickly made up for lost time on the gun line by destroying a Viet Cong command post and nine bunkers in support of the 173 Airborne Brigade, who were operating about 50 miles (80 km) north of Nha Trang. The next day New Jersey maneuvered into the waters of the Baie de Van Fong to fire at Viet Cong command posts, but poor visibility of the target area prevented any damage estimates.
On the night of 23 October New Jersey steamed north to rearm before taking up position in support of the 3rd Marine Division 25 October. That day she shelled enemy troops located by a spotter plane. The next day New Jersey engaged targets of opportunity, destroying 11 structures, seven bunkers, a concrete observation tower, and an enemy trench line. She also received hostile fire when North Vietnamese gunners attempted to strike at New Jersey with artillery positioned near Cap Lay. Some ten to twelve rounds were launched at New Jersey; however, the rounds fired landed well short of the battleship. Aerial spotters were called in to look at the suspected gun position; they reported no artillery present but fresh tire tracks leading to a concealed area, suggesting that there had been artillery there earlier. Armed with this information New Jersey fired five 16 inch shells at the site, but in the darkness spotters were unable to confirm any hits.
On 28 October New Jersey steamed south to engage Communist targets. During the shelling aircraft spotting for the battleship reported taking heavy anti-aircraft fire to the extreme north of the target zone; subsequently, New Jersey altered her fire to silence the site with her big guns. The next day New Jersey leveled 30 structures, destroyed three underground bunkers, and shelled a Viet Cong trench line. That afternoon an aerial observer located an enemy artillery position on a hilltop southwest of Cap Lay. New Jersey responded by firing six 16 inch rounds at the site, destroying it. Follow up assaults on 30 October destroyed a Communist resupply area and an anti-aircraft site.
Upon completion of this mission New Jersey steamed south, taking a position off Da Nang and Point DeDe to lend naval gunfire support to the US 1st Marine Divison operating in the area. On 2 November New Jersey commenced firing operations against nine positions, but the heavy foliage in the area prevented spotters from seeing the results of the shelling.
On 4 November New Jersey received orders to reinforce southern II Corps near Phan Thiet; she arrived on station later that night. The next she answered eight call fire support missions from the 173rd Airborne Brigade, in the process destroying eight Viet Cong bunkers and five structures. On 11 November New Jersey departed Vietnamese waters to replenish; she returned to the gunline 23 November and relieved Galveston , taking up position in support of the U.S. Army's Americal Division. That afternoon New Jersey's 5-inch (127 mm) guns shelled enemy buildings, destroying 15 structures and inflicted heavy damage on 29 others.
On 25 November New Jersey launched the most destructive shore bombardment of her Vietnam tour. For the next two days the battleship concentrated her fire at Viet Cong storage areas near Quang Ngai, destroying 182 structures and 54 bunkers, inflicting heavy damage to 93 structures, and demolishing several tunnel complexes before departing for Point Betsy near Hue 27 November to support the 101st Airborne Division. Between 2 December and 8 December New Jersey returned to aid the 3rd Marine Division, shelling Viet Cong bunker complexes for the Marines operating around the Da Nang area before departing for Singapore 9 December. On 26 December New Jersey returned to the gunline, taking up station off Tuy Hoa in support of the Republic of Vietnam's 47th Army Division. For the next three days New Jersey fired her guns to support the II Corps, in the process destroying Viet Cong bunkers and supply depots and neutralizing enemy cave posts. New Jersey would remain in the waters of the DMZ until after New Years, shelling Communist bunkers for ground troops until leaving to support the 1st Marine Division 3 January.

Throughout January and into February New Jersey operated in support of the Marines and Americal Division( Russell  Beach) On 10 February the battleship left to reinforce the 2nd ROK Marine Brigade operating near Da Nang. The battleship's target was a suspected subterranean staging area for a Viet Cong regiment. New Jersey's big guns went to work on the complex, firing 16 inch shells into tunnels and bunkers to aid the ground troops. On 14 February the battleship steamed south of the DMZ to provide support for the 3rd Marine Division, in the process destroying an anti-aircraft site with her big guns. The next day New Jersey fired on an enemy rocket site northeast of Con Thien, destroying the facility, then trained her guns on known Communist positions to harass Viet Cong forces. On 22 February New Jersey responded to an urgent request for fire support from a besieged outpost near the DMZ. For the next six hours New Jersey fired her guns, ultimately repelling the attacking force.

For the remainder of February and into March New Jersey shelled targets along the DMZ. On 13 March the battleship departed the gunline bound for Subic Bay. She returned to action on 20 March, operating near Cam Ranh Bay in support of the Republic of Korea's Ninth Infantry Division. For the next week New Jersey patrolled the waters between Phan Thiet and Tuy Hoa, shelling targets of opportunity along the coast. On 28 March New Jersey took up station south of the DMZ to aid the 3rd Marine Division, remaining there until 1 April, whereupon New Jersey departed for Japan.
 During the battleship's tour of duty along the gunline in Vietnam, the USS New Jersey had fired 5,688 rounds of 16 inch shells, and 14,891 five inch shells,