The extraction of river sand is causing increasing destruction to rivers, leading to a growing awareness of its environmental impact. Additionally, the disposal of palm oil shells from the palm oil industry contributes to environmental pollution. This research aimed to determine the effect of different curing regimes on the durability of oil palm shell (OPS) lightweight aggregate concrete when sieved palm oil fuel ash is used as a sand replacement. Three lightweight aggregate concrete mixtures were created by replacing sand with varying percentages of sieved palm oil fuel ash (0%, 10%, and 20%). Two types of curing methods were employed: water curing and air curing. The specimens were tested for compressive strength, sulphate resistance, and carbonation. The results showed that water-cured concrete mixtures had better durability than air-cured ones. Among all the mixtures, the water-cured concrete with 10% sieved palm oil fuel ash exhibited the least deterioration when exposed to sulphate attack. Additionally, all water-cured specimens containing up to 20% sieved palm oil fuel ash were resistant to carbonation, unlike the air-cured specimens. In conclusion, incorporating palm oil fuel ash in concrete can reduce the waste management issues faced by palm oil mills.