To negate a conditional statement, you can add the "not" operator or use the negation symbol (¬) before the condition. In most programming languages, the "not" operator is represented by the exclamation mark (!). For example, if your original statement is "if (x > y)", the negated statement would be "if (!(x > y))" or "if (x ≤ y)". This means the code within the conditional block will execute when the original condition is false.