Siddhraj Jaysinh was a notable king of the Solanki dynasty. He was also known as Siddhraj Solanki. After the death of his father Karandev Siddhraj ascended the throne of Patan. Patan's condition was worse in the last days of Karandev. His grand father Bhimdev's descendants attempted their best to overpower the throne from child Jaysinh. His mother Minaldevi, Maha Mantri Santu and Munjal Mehta in the initial stages played a great part to prevent them in their attempts. Jaysinh ascended to the throne in 1096. Hence between the years of his father's death and his actual takeover was safeguarded by his mother and his mantris. During those early days his mother with her child Jaysinh remained concealed in Saurashtra in disguise. She left the administration of Patan in the hands of Mantri Shantu. Malav king Narvarma attacked Patan in those days. Thus the mantri accepted Narvarma's Kingship for Jaysinh as Samant of Malva. However later Jaysinh regained his kingdom. He also weakened the successors from his grand father Bhimdev's first wife Bauladevi. Siddhraj Jaysinh was after the life of Kumarpal who was the successor of queen Bauladevi. He was a probable candidate for patan's throne. Kumarpal hid himself from Jaysinh for more than 30 years. Siddhraj had also conquered the Malwa defeating king Yashovarma and south Gujarat.

Siddhraj wished to marry the princess Ranakdevi, but his vassal, Ra Khengar, the Chief of Junagadh had already married her before he could do so. Thus Siddharaj attacked the mountain-fortress of Junagadh. He killed Ranakdevi's husband and her sons but Ranakdevi rejected Siddharaj's advances for marriage. She was forcibly brought to Wadhwan where she committed the ritual of Sati at this place to guard her honour. Siddharaj took the title of 'Barbarak Jishnu' and also 'Siddhraj' after controlling Bhil king Barbarak. He became Chakravarti after acquiring total control of the region under old Gurjar Chakravarti kings. He has been credited with renovated and widened the lake constructed by Durlabhraj and named it as Sahastraling Lake. He constructed two lakes in the memory of his mother. He also renovated Rudramahal. During his reign Patanhad prospered in education, religion and commerce. He had given shelter to many scholars of different religion and castes. Other notable figures of his time included his, Prime Minister Munjal Mehta, Kak and leading Courtier Udayan Mehta. Siddhraj Jaysinh died in 1143. The throne remained without King for 18 days. Thereafter Kumarpal was suddenly declared King of Patan.