Before the summit, Prince Mohammed had visited the United Arab Emirates, Bahrain, Egypt and Tunisia.
President Recep Tayyip Erdogan said that Turkey's insistence on finding the truth behind the recent killing of journalist Jamal Khashoggi was not aimed at damaging the Saudi royal family.
Saudi Arabia has said that 21 people are in custody and vowed to keep probing the killing of Khashoggi, who was killed and dismembered after visiting the kingdom's Istanbul consulate to handle paperwork for his planned wedding. Based on these and similar records, the agency concluded with "medium-to-high confidence" that Prince Mohammed "personally targeted" Khashoggi and "probably ordered his death".
May met leaders including the Canadian prime minister, Justin Trudeau, the Australian prime minister, Scott Morrison, and the Japanese prime minister, Shinzō Abe, all of whom expressed some scepticism about the state of her Brexit deal.
Saudi Arabia has been under acute pressure to come clean on the murder of Mr Khashoggi in its Turkish consulate in October.
The Journal also reported on Friday that in August 2017 MBS had told associates if his efforts to persuade Khashoggi to return to Saudi Arabia were unsuccessful "we could possibly lure him outside Saudi Arabia and make arrangements".
It was jointly denounced by 17 intellectuals, journalists, Muslim scholars and other figures in the North African country, in a statement obtained by AFP. It will also develop stronger ties in trade, investment, energy and in the cultural and educational sectors.
Kremlin spokesman Dmitry Peskov said that "good personal relations are the basis for effective bilateral cooperation" when asked about the moment between the two world leaders.