Determination of pesticides is important for human health. Sensors are one of the best solutions because they do not require a long sample preparation and can be used not only in a laboratory. Electrochemical sensors can be easily minimised and employed for the detection of pesticides in liquid samples such as ground or wastewater. Conducting polymers have a few roles in electrochemical sensors, therefore, they can be good candidates for sensor development. Electrochemically co-polymerised folic acid and riboflavin as well as folic acid and L-lysine were employed for the detection of atrazine using square wave voltammetry. The co-polymer composition was optimised and characterised electrochemically and spectroscopically. The optimal composition of polyfolic acid and poly-L-lysine co-polymer electrosynthesised from the monomer ratio 1:10 was the best in terms of stability and sensitivity to atrazine. The best method was the square wave voltammetry showing the best sensitivity to atrazine 198 ± 1 μA/μM cm2, and the limit of detection was 14.8 nM. However, the sensitivity in tap water was significantly lower but still suitable for atrazine detection by the spike method.