Smartphone are generally used by adults for different purposes and are more prone to be addicted. Increased use of Smartphone has caused alterations in upper cervical posture. Objective of the study was to find out the activation of deep neck flexor muscle on neck pain due to smartphone addiction. The smartphone addiction scale was used to evaluate the addiction on 30 participants, then for those addicted and complaining of Neck pain while using smartphone Neck Disability Index was used. Then deep neck flexor activation exercise was performed for 3 weeks every alternate day 3 times a day for 15 repetitions. After 3 weeks again evaluation was done. The result showed there was significant improvement in neck disability and pain in participants. It was concluded that deep neck flexor activation is suitable to treat neck pain in smart phone addicted people for reducing pain and disability.