Fullerenes C₆₀, C₇₀, and C₈₄ may be readily encaged within a hydrogen-bonded dimeric capsule, based on two concave cyclotriveratrylene (CTV) scaffolds each bearing three self-complementary 2-ureido-4-[1H]-pyrimidinone (UPy) subunits. We herein report NMR and CD studies—complemented by dispersion-corrected density functional theory calculations—aiming to characterize such capsule-fullerene complexes both structurally and energetically. Six fullerenes are considered: in agreement with experiment, calculations find that encapsulation is most favorable for C₈₄ (on a par with C₉₀), and follows the trend C₆₀<C₇₀<C₇₆<C₇₈<C₈₄≈C₉₀. As also found by NMR, the most stable capsules are formed by monomers of identical stereochemistry; with UPy and the CTV’s OMe groups in mutual anti orientation; and UPy-CTV ethylene linkers within the capsular surface plane. Up to C₇₈, encapsulation is favored by increasing host-guest contacts, but the trend is thereafter increasingly inhibited by growing capsule strain.