Prime Minister Prayut Chan-o-cha met with Saudi Crown Prince Mohammed bin Salman on Friday, signing agreements to expand diplomatic relations restored this year more than three decades after Saudi Arabia downgraded ties over a jewellery theft.
The two leaders presiding over the signing of five agreements pledging to increase trade and investment between the two countries, promote tourism and deepen cooperation in energy.
Thailand is hoping that its improving relationship with Saudi Arabia could give it an economic boost.
Saudi Arabia's expansion of its diplomatic circle comes in the aftermath of international condemnation over the 2018 murder of Washington Post journalist Jamal Khashoggi, who was murdered and dismembered by Saudi agents inside the kingdom's consulate in Istanbul.
Gen Prayut held bilateral talks with the crown prince on the sidelines of the Asia-Pacific Economic Cooperation (Apec) summit. Saudi Arabia was invited as a guest of the Apec host country.
"Cooperation in trade, investment and labour is already underway," government spokeswoman Rachada Dhnadirek said ahead of the meetings.
The two countries restored full diplomatic ties in January when Gen Prayut visited the country at the invitation of the crown prince.
Saudi Arabia downgraded diplomatic relations in 1989 following a row over the theft of around $20 million of jewels by Kriengkrai Techamong, a Thai janitor working in the palace of a Saudi prince, in what became known as the "Blue Diamond Affair".
A large number of the gems, including a rare blue diamond, were never recovered. The theft remains an unsolved mystery and was followed by the execution-style murder in Thailand of three Saudi diplomats.
"The restoration of ties has mutual benefits for both countries," the crown prince said, adding that investment, infrastructure and public health were important areas.
"Overcoming the Blue Diamond issue is a net positive for both countries," said Ben Kiatkwankul, partner at government affairs advisory, Maverick Consulting Group.
Saudi Arabia is seeking to diversify the economy away from oil into industries like food and agriculture, which makes Thailand a good partner, he said, while Thailand stands to benefit from energy-related projects and medical tourism.
Since January, exchanges between the two countries have included an agreement between state-owned energy firms Saudi Aramco and PTT Plc for cooperation in carbon capture and crude oil sourcing. In October, Thailand hosted the controversial Saudi-backed circuit, LIV Golf Invitational.
Saudi Investment Minister Khalid al-Falih in November also attended a business forum in Bangkok meeting agriculture firms like CP Foods.