Consumption of ultra-processed foods has increased alarmingly, representing a risk to children’s health. Different techniques in marketing to kids (M2K) used on food labels are influencing the purchasing decisions of these products. This study aims to provide useful information about M2K found in labeling of food products sold in a supermarket chain in Lima, Peru and to determine its relationship with critical nutrient content. This was an observational, correlational, descriptive study. Data were collected by photographing the front-of-pack (FoP) of 2747 product labels sold in three supermarkets in Lima, but only those that met all the inclusion criteria were evaluated (n = 1092). A relationship was found between the use of techniques in marketing to kids and the level of critical nutrient regarding saturated fat (PR = 0.56; CI95%: 0.52–0.63), total sugar (PR = 1.70; CI95%: 1.64–1.77), and sodium (PR = 1.05; CI95%: 1.03–1.07). Particularly with sugar, the presence of M2K is a risk factor. New regulatory policies for the use of these food labeling techniques should be implemented to improve children’s health at the population level.