Decision-making is an important attribute that a teacher needs to possess to be effective; this is especially so for EFL teachers when faced with the complicated dynamics of classroom interaction. The best rational decisions get considerably vitiated because of cognitive biases, thereby, leading to less-than-optimal teaching performances. In the present study, authors develop and validate an English language teachers' cognitive bias scale, referred to as EFLT-CBS, which measures cognitive bias among EFL teachers. The study involved a sample of 252 EFL teachers, including 91 males and 160 females with diverse educational backgrounds and teaching experiences, recruited through convenience and snowball sampling. Items were developed based on Dwyer’s (2018) classification of cognitive biases in an educational context. The Rasch rating scale model was employed to refine the scale, resulting in a validated 16-item EFLT-CBS with strong psychometric properties. Significant differences were found by gender, with males showing more cognitive bias than female teachers. Implications of the study for the treatment of cognitive bias among foreign language teachers are discussed.