--- - |2 Abstract Recent research has shown that children as young as age 3.5 show behavioral responses to uncertainty although they are not able to report it explicitly. In this study, we tested the hypothesis that some form of metacognition is already available to guide children's decisions before the age of 3. Two groups of 2.5‐ and 3.5‐year‐old children were asked to complete a forced‐choice perceptual identification test and to explicitly rate their confidence in each decision. Moreover, participants had the opportunity to ask for a cue to help them decide if their response was correct. Our results revealed that all children asked for a cue more often after an incorrect response than after a correct response in the forced‐choice identification test, indicating a good ability to implicitly introspect on the results of their cognitive operations. On the contrary, none of these children displayed metacognitive sensitivity when making explicit confidence judgments, consistent with previous evidence of later development of explicit metacognition. Critically, our findings suggest that implicit metacognition exists much earlier than typically assumed, as early as 2.5 years of age. - Developmental Science, EarlyView.