Serum prealbumin is considered to be as important as albumin in the nutritional status assessment. However, there is relatively little evidence of its advantage over the commonly used albumin. This study investigated the use of prealbumin compared to albumin as a marker of nutritional status in adults singly and dually infected with human immunodeficiency virus (HIV) and intestinal helminths, with or without inflammatory conditions, in different body mass index (BMI) categories. This cross-sectional study was conducted in a periurban setting in KwaZulu-Natal, South Africa. Multivariate multinomial logistic regression models were fitted to investigate the effect of prealbumin and albumin in nutritional assessment among HIV and helminth individuals with or without inflammation, indicated by elevated and normal C-reactive protein (CRP) levels. In normal CRP, albumin was significantly lower in unadjusted BMI [RRR = 0.8, p = 0.001] and in normal weight [RRR = 0.7, p = 0.003] and overweight [RRR = 0.5, p = 0.001] participants. In elevated CRP, albumin was significantly lower [RRR = 0.8, p = 0.050] and prealbumin was significantly higher in unadjusted BMI [RRR = 1.2, p = 0.034] and overweight [RRR = 1.4, p = 0.052] individuals. The current study found that prealbumin can differentiate between inflammation-induced reduction of albumin and true malnutrition in adults singly or coinfected with HIV and intestinal helminths in the presence or absence of inflammation in various BMI categories.