Deep eutectic solvents (DESs) have shown potential as novel media to support molecular aggregation. The self-aggregation behavior of two common and popular carbocyanine dyes, 5,5',6,6'-tetrachloro-1,1'-diethy1-3,3'-di(4sulfobuty1)-benzimidazole carbocyanine (TDBC) and 5,5'-dichloro-3,3'-di (3-sulfopropy1)-9-methyl-benzothiacarbo cyanine (DMTC), is investigated within DES-based systems under ambient conditions. Although TDBC is known to form J aggregates in basic aqueous solution, DMTC forms H-aggregates under similar conditions. The DESs used, glyceline and reline, are composed of salt choline chloride and two vastly different H bond donors, glycerol and urea, respectively, in 1:2 mol ratios. Both DESs in the presence of base are found to support J aggregates of TDBC. These fluorescent J-aggregates are characterized by small Stokes'-Shifts and subnanosecond fluorescence lifetimes. Under similar conditions, DMTC forms fluorescent II-aggregates along with J-aggregates within the two DES-based systems. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) below its critical micelle concentration (cmc) to a TDBC solution of aqueous base-added glyceline shows the prominent presence of J-aggregates, and increasing the CTAB concentration to above cmc results in the disruption of J-aggregates and the formation of unprecedented H-aggregates. DMTC exclusively forms H-aggregates within a CTAB solution of aqueous base-added glyceline irrespective of the surfactant concentration. Anionic surfactant, sodium.dodecylsulfate (SDS), present below its cmc within aqueous "base-added DESs supports J-aggregation by TDBC; for similar SDS addition, DMTC forms H-aggregates within the glyceline-based system whereas both H- and J-aggregates exist within the reline-based system. A comparison of the carbocyanine dye behavior in various aqueous base-added DES systems to that in aqueous basic media reveals contrasting aggregation tendencies" and/or efficiencies. Surfactants as additives are demonstrated to control and'modulate carbocyanine dye self-aggregation within DES-based media. The unique nature of DESs as alternate media toward affecting cyanine dye aggregation is highlighted.