An apparatus for estimating bio-information of an object of interest may include a processor configured to obtain a plurality of pulse wave signals of an object via a plurality of channels, determine a plurality of oxygen saturation values corresponding to the plurality of channels based on the plurality of pulse wave signals, select a channel to be used for estimating the bio-information of the object of interest from among the plurality of channels based on the plurality of oxygen saturation values, and estimate the bio-information of the object of interest based on a pulse wave signal corresponding to the selected channel.