Example methods are provided for a computer system to validate routing information in a software-defined networking (SDN) environment. The method may comprise obtaining routing information associated with a logical router in a first autonomous system and network topology information associated with the first autonomous system. The routing information may specify multiple first routes to respective multiple first networks, and the network topology information may specify multiple second routes that connect the logical router to respective multiple second networks. The method may also comprise validating the routing information based on the network topology information to determine whether the multiple first routes are valid based on the multiple second routes; and in response to determination that a particular first route from the multiple first routes is invalid, configuring the logical router to exclude the particular first route from route advertisement information destined for a second autonomous system.