Friend relationships and location information are the biggest privacy concerns for the users in mobile Online Social Networks (mOSNs). Existing solutions save these two kinds of privacy information in two different servers, i.e., Social Network Server (SNS) and Location Based Server (LBS), and employ some encryption protocols to map each other to provide the location-sharing service among friends and strangers. However, this distributed architecture incurs large communication overhead between SNS and LBS, and great storage burden as well. In order to overcome these shortages, we propose a centralized privacy-preserving location-sharing system, named CenLocShare. It integrates SNS and LBS into one server, i.e., Location-storing Social Network Server (LSSNS), and uses the dummy locations and the dedicated mapping protocols between LSSNS and Cellular Tower (CT) to share privacy-preserving locations. Its safety is validated by the security analysis. Furthermore, we implement the prototype of CenLocShare and do some comparisons with other systems. The thorough experiments indicate our system decreases the query time for friends’ locations and the storage space CenLocShare is more suitable and effective in the context of mOSNs © 2017 Elsevier B.V.