The authors describe a "turn-on" fluorometric method for determination of β-carotene. It is based on competitive host-guest interaction between rhodamine 6G (R6G) and β-carotene and graphene oxide nanoparticles that were functionalized with β-cyclodextrin (β-CD)-modified polyethylenimine (β-CD-PEI-GO). On addition of R6G to a solution of β-CD-PEI-GO, its fluorescence is quenched because of the inclusion of R6G into the β-CD moiety. Both Förster resonance energy transfer and electron transfer are likely to occur. On further addition of a sample containing β-carotene, it will replace R6G in the cavity, thereby releasing R6G to the bulk solution. This is due to the stronger affinity of β-carotene for β-CD in the complex, but also because of repulsion between the positively charged β-CD-PEI-GO complex and the positively charged R6G dye. The displacement of R6G by β-carotene leads to fluorescence recovery whose efficiency (expressed as F/F 0 ) is related to the β-carotene concentration in the range from 0.1 to 4.0 μmol⋅L‾ 1 . The detection limit for β-carotene is 5.4 nmol⋅L‾ 1 which is lower than that of any other optical method.