Online information search has become essential to knowledge construction. Digital information technologies are proliferating, and students are expected to be able to use them to manage the enormous volumes of information available online. Past research has shown that students of all ages may lack the ability to search for and find information effectively and efficiently. Therefore, it is necessary to determine ways of helping students to best apply search strategies to achieve their search goals. A review of relevant empirical studies published between 1995 and 2017 was conducted to examine the use of metacognitive scaffolding for online information search. Based on 36 studies, the reviewed metacognitive scaffolding strategies were all effective in enhancing both the process of searching and searching performance. Age was found to moderate this effect for search outcome, but not for search process. The results are discussed in online search contexts.