The present work is aimed at studying the interactions between mixed micelles of nonionic surfactants, Tweens (Tween 20, Tween 40, Tween 60, and Tween 80) and cationic surfactant, dodecylbenzyldimethylammonium chloride (C12BzCl), and to draw a comparison between the effect of different Tweens with respect to fatty acid chain present in them. Both from the industrial and research point of view, the present day need for newer materials has been diverted to surfactant-additive systems rather than single surfactant systems because of the great fundamental, technological, and biological importance associated with the mixed micelles. Moreover, Tweens being biocompatible, stable, and relatively nontoxic can be used to enhance the efficacy of benzalkonium (Bz)-based disinfection products. Conductivity and surface tension techniques have been employed to determine various micellar parameters like critical micellar concentration (cmc), degree of counterion binding (beta), standard free energy of micellization (Delta G(mic)(o)), excess free energy of mixing (Delta G(ex)(o)),), interaction parameter (beta(m)) and activity coefficients for the Tweens (f(1)) and C12BzCl (f(2)) in the mixed micelles using Rubingh's, Motomura's, and Maeda's approach. The negative values of beta(m) indicate synergism in the mixtures which is highly beneficial as it reduces the total amount of surfactant used in a particular application resulting in reduction of cost and environmental impact. The results have also been discussed in terms of short-range interactions between the two types of surfactants.