A chemosensor NBD-PMA with colorimetric and fluorometric responses for Pd²⁺ cations has been described. NBD-PMA selectively coordinated Pd²⁺ cations with a colour change from bright yellow to pink, which enabled detection of Pd²⁺ cations in environmental water samples with the naked eye. NBD-PMA also exhibited high selectivity and sensitivity for Pd²⁺ cations in fluorometry even in the presence of other metal cations, which makes it practically applicable for detecting Pd²⁺ cations in environmental samples and in living cells.