The impact of natural polymeric dispersants, that is, carboxymethyl cellulose and guar gum, on the flotation selectivity was investigated on a flotation deinking pilot plant. Their effect on pulp flocculation, air bubble size, and gas hold-up was determined by implementing a fiber flocculation sensor, an automated bubble measurement device, and a gas hold-up sensor on the pilot cell. Dispersants reduced pulp flocculation and induced an increase in gas hold-up and a slight decrease in the air bubble size. Their addition promoted ink removal and, at the same time, depressed fiber entrainment and mineral fillers flotation, thus increasing exceptionally the flotation selectivity.