Location-related mobile social network services are popular nowadays, and their methods to obtain end users’ location information are based on people's self-report location claims, using mobile devices to check positions and send them back to the service providers. However, this mechanism has a serious vulnerability that makes malicious users be able to access restricted resource by transmitting fake locations. Both academic and industrial researchers are recently aware of this problem's importance since the commercialized trend of location-related mobile social network services. To address this issue, we propose mobile phone-based physical-social location, a mobile phone-based location proof system to verify users’ location claims and defend various fake location information. Our core idea is that a user's location claim can be proved by a set of selective physical encountered people serving as “witnesses” who are co-located with him/her in that area. The system is composed of proof generation and verification. In the proof generation phase, we leverage a certain number of co-located people to generate certificates as location proofs during their encounters via bluetooth interface. In the verification phase, we propose an efficient verification scheme to make our system accurate and adaptive. We have implemented the MPSL system using real world Nokia N82 (Nokia, Espoo, Finland) phones. Our experimental results show that our mobile phone-based system can achieve high verification accuracy and good performance. Copyright © 2014 John Wiley & Sons, Ltd.