Due to the high penetration of non-dispatchable renewable sources, the power system is facing a challenge in operational flexibility. As more and more renewables are replacing conventional generations, integration of energy storage system (ESS) is crucial in providing faster response in balancing and grid services. However, ESS, of today, faces many regulatory and market challenges in order to be deployed in the power system operation. This is also hindering the progress towards the decarbonisation of smart grid network. This paper proposes ESS as a possible “Flexibility Resources” and its potential role in the future smart grid network. This will further support the regulatory authority to define this classification for ESS to overcome the barriers and to procure and valorise the range of services that the ESS can provide. The potential benefits of ESS as Flexibility Resource will facilitate increased participation of storage in different electricity markets and improve the flexibility of smart grid operation with high penetration of renewables. Moreover, it will solve the ownership issues and hence, will be beneficial for all the stakeholders