Islam is the final religion of Allah Almighty and it is meant to guide all the people of all the times till the Day of Judgment. In order to implement this message of guidance in this world and to give it a practical shape Allah Almighty sent Prophet Muḥammad ( صلى الله عليه وسلم ) who conveyed this message to the people with the help of great wisdom and excellent advice and establish a society on the basis of this message. The Sīrah of Prophet Muḥammad ( صلى الله عليه وسلم ) provides such rules and regulations which are helpful in addressing the needs of individuals and society of all times and ages. Although the world has been changing ever since its creation, yet the pace of change in the last one hundred years or so has been the most rapid ever. The effects of these changes were beyond the limitations of time and region and therefore they directly affected the Muslim world as well. Muslim scholars did not ignore these changes but realized their responsibilities and wrote such books of Sīrah which provided guidance in connection with these rapid changes and conditions. This research has highlighted various approaches and trends of Sῑrah writing with a special reference to Muslim international law. This research has elaborated the basis of international laws of the West and Muslim international law. The inception of Muslim international law and modern international law, their origins, their sources, their basic principles, their histories and their validities were highlighted. The study has given a detailed comparison between both the laws. The study has compared and analyzed the selected prominent books of Sīrah. The books written on Sīrah in twentieth century contain detailed discussions on various issues of international law. This research has discussed the following issues: as the concept of state in Islam, the rules and regulations for the relationship with the Non- Muslims, the Non-Muslims citizens of an Islamic State, Jizyah, impartiality and the ideas of peaceful mutual existence, injunctions of war and reconciliation with Non-Muslims, the treaties, the rights of the war prisoners, the Islamic concept of Jihād, and the international conflicts etc. The opinions of the authors of the selected prominent books have been compiled in this research and a comparative and analytical study of these opinions has also been conducted.