To store the sensitive and large amount of information on mobile devices is not recommended as it can be lost or stolen and the storage capacity is limited. Even the services of the single-cloud storage provider are not preferred due to issues like limited free storage, vendor lock-in and data loss. To deal with these issues, multi-cloud storage services are preferred which provide a single platform for multiple cloud storage services. From recent studies, it has been observed that the use of existing multi-cloud storage systems is uncommon by mobile users because they have lots of issues when accessed through resource-constrained mobile devices as they are consuming a lot of resources like CPU, battery and data (Internet usage) of mobile devices. So, in this paper, an efficient and secure multi-cloud storage approach is developed using the concept of fog computing to leverage augmentation of multi-cloud storage services on resource-constrained mobile devices.