Banks offer loans to support many projects; however, some of these projects may not give adequate consideration to the environment. Little is known regarding the extent to which banking customers experience guilt when discovering that their bank supports projects that disregard the environment. An experiment with 313 participants was conducted, and the results showed that customers do experience guilt when discovering that their bank supports projects that do not give adequate consideration to the environment. This study found that guilt drives perceived consumer effectiveness and negative word‐of‐mouth regarding banking projects that neglect environmental considerations but not attitudes towards green banking. Negative word of mouth, but not the attitude towards green banking, mediates the effect of perceived consumer effectiveness on the intention to use green banking services. Negative word‐of‐mouth, rather than attitudes towards green banking and its perceived consumer effectiveness, drives the intention to use green banking services. These findings imply that banks need to encourage their customers to perceive that they are eco‐friendly to avoid a significant loss of customers.