Odor-induced sweetness enhancement has become a method that does not change consumer acceptability and can effectively reduce the sugar content in food products. In this study, the volatile compounds in “Red Blush” grapefruit juice were investigated by headspace solid-phase microextraction, solvent-assisted flavor evaporation, and gas chromatography–mass spectrometry (GC–MS) combined with gas chromatography/olfactometry-associated taste (GC/O-AT). A total of 59 volatiles were identified by GC–MS, and 32 volatiles were identified as key aroma compounds with an odor activity value ≥ 1 or aroma intensity ≥ 3. GC-O/AT analysis screened 10 odorants associated with sweetness. Furthermore, we examined whether odor could enhance the sweetness in sucrose solutions or sucrose–citric acid mixed solutions through sensory experiments. The results showed that eight odorants could significantly achieve the sweetness enhancement effect at 50 g/L sucrose solution. Ethyl propanoate, ethyl butyrate, ethyl 2-methyl butyrate, ethyl hexanoate, and terpinolene could also enhance the sweet taste in the sucrose–citric acid mixed solution. This study provides more theoretical support for aroma–taste interactions in the citrus-flavored system and compensates for sugar reduction in the food industry.