When carbonation reaches the depth of the rebar embedded into the concrete, the high alkalinity of the concrete pore solution is neutralised and hydration products are dissolved. As carbonation progresses, the corrosion could extend enough to deteriorate the structural performance. In this paper, a time-dependent structural reliability analysis method, taking the carbonation into consideration, is proposed. To predict the corrosion process of reinforced concrete (RC) structures, spatial variability of corrosion has to be considered. A computational procedure to integrate the spatial variability of corrosion due to carbonation into life-cycle reliability assessment of existing RC structures is established. An illustrative example of a RC structure subjected to carbonation is presented. The emphasis is placed on investigating the effects of the spatial variation of inspected carbonation depths on the reliability estimates of RC structures.