This study is to examine the relationship between terrorism and state security, a case study of al- Shabaab activities in Kenya, 2010-2015. Chapter one of study, started by differentiating terrorism from common law crimes and other offences because the motivation is not for financial gain, a distinction from other organized criminal behavior. It clearly explains that, terrorism is by its nature an organized and planned event or policy. Besides other developed countries like the United States and Israel, terrorist have in the recent years attacked in Kenyan soil making the Kenya state security to embark on the incursion of Somalia in order to exterminate the Al- Shabaab extremists. This however has put Kenya state security into a great danger. In regard to this, the study seeks to determine the cause of terror, the impact of Al-Shabaab terrorist activities and the effectiveness of Kenyans counterterrorism strategies on Kenyan state security. Since the study is descriptive in nature it offer a precise illustration of dynamics relevant to research question. It will employ qualitative and qualitative methods. Qualitative interviews and structured questionnaires will thus be used. Chapter two of the study is based on the effect of regional terrorism on state security. This section begins by the causes of terrorism like poor security and high levels of corruption. It further explains its counter terrorism strategies like peaceful measures instead of engaging in force with the trained military. From the major attacks that happed like the churches in Kenya has denied freedom of movement, association, worship many other rights and freedom associated with a secure environment. This has caused directly or indirectly effect to financial also there is massive damage to property and communication systems. On the 7th of August, 1998, the Al Qaeda network simultaneously executed twin attacks in Tanzania and Kenya, targeting the U.S. embassy. The Al Qaeda bombed the Paradise hotel in Kikambala on the North Coast of Kenya in a deadly attack. In the recent years attack by unidentified gunmen on Garissa churches probably signifies a different dimension in Kenya‘s demeanor of terrorist violence, which further suggests that a physical war of religions others include Attack on a Bus in Eastleigh Suburb, Machakos bus terminus in Nairobi, Westgate mall amongst many other. Though the KDF is now in control of southern Somalia, the question is how long it would take after a KDF withdrawal for al-Shabaab forces to begin rebuilding their movement by retaking important ports like Kismayo. The study recommends that the government help in raising the capacities of countries and organizations in the region. While religious leaders are emerging as key players in the area of counterterrorism, they are faced with many challenges rooted in the socioeconomic and political conditions.