Ro-34 was on the surface off San Cristobal on the evening of 7 April 1943 when Strong again made radar contact on her at 21:51 Lima Time at a range of 9,350 yards (8,550 m) bearing 150 degrees true from Strong. Strong closed the range and illuminated Ro-34 with her searchlights, then opened fire with her 5-inch (127 mm) guns and 40mm and 20mm antiaircraft guns. She scored at least three 5-inch (127 mm) shell hits, and Ro-34 assumed a 10-to-15-degree down-angle by the stern and submerged. Strong dropped two patterns of depth charges and her crew observed debris rising to the surface at 10°05′S 162°08′E, marking the sinking of Ro-34.
On 16 April 1943, Ro-34 was ordered to return to Rabaul, but she did not acknowledge the order. On 2 May 1943, the Imperial Japanese Navy declared her to be presumed lost in the Solomon Islands with her entire crew of 66. The Japanese struck her from the Navy list on 14 July 1943.