In the context of global climate change, rising sea levels and ground subsidence are putting the Yellow River Delta at serious risk of seawater inundation, posing a threat to the future sustainable development of the Yellow River Delta. Projecting the relative sea level change in the Yellow River Delta due to ground subsidence can help to gain insight into the current seawater inundation risk and take timely measures to address it. First, the average subsidence rate from February 2016 to September 2019 was obtained based on SBAS-InSAR technology, and the accuracy of the InSAR results was further improved by using level data, with the maximum average subsidence rate reaching -357 mm/a after compensation. Combined with high-resolution imagery, it was found that the main cause of ground subsidence is the extraction of underground brine, oil, and gas. Second, combined with the distribution of subsidence sites, it was found that natural sedimentation continued to influence coastal subsidence. Finally, a seawater inundation model was developed using an active algorithm that combines the results of surface subsidence with confidence intervals for sea level rise under the SSP2-4.5 scenario in the IPCC AR6. The model results show that by 2030, 2050, and 2100, the percentage of seawater inundation area will be 6.76%~6.84%, 10.81%~11.11%, and 28.71%~30.92%, respectively, at the current subsidence rate. When the subsidence rate decreases to 50% and 25% of the current rate, the percentage of seawater inundation area is 5.84%~5.91%, 8.20%~8.40%, and 19.05%~21.51%, and 5.34%, 6.60%~6.69%, and 9.89%~11.62%, respectively. Compared to the threat of absolute sea level rise, the containment of subsidence rates will substantially reduce the risk of seawater inundation. The main types of land inundated by seawater are construction land, arable land, water bodies, and salt flats. The rate of seawater inundation of construction land, arable land, and water bodies will continue to accelerate over time. The results of this study can be used as a reference by relevant authorities to manage the development of soil and water resources as well as for disaster prevention in the Yellow River Delta.