The World Economic Forum revised up the country competitiveness for 2014-15 to 31 from 37 in the previous year in the rankings of 144 countries.
The overall score climbed to 4.7 from 4.5 of the previous year.
The country moves up 12 places in the macroeconomic environment and now ranks 19th, its best showing among the 12 pillars.
WEF noted that all the data used in the assessment were collected before the May 22 military coup.
"In 2013, Thailand almost balanced its budget and reduced inflation to 2%. Public debt remained stable and the savings rate was high," WEP said in its Global Competitiveness Report 2014-2015.
The country continues to do well in financial development (34th) and improves its strong showing in market efficiency (30th, up four).
"However, market competition remains limited by a number of barriers to entry, especially those affecting foreign investments," the report said.
Governance is a major area of concern. Political and policy instability, excessive red tape, pervasive corruption, security concerns, and high uncertainty around property rights protection seriously undermine the institutional framework, it said.
In most of these areas, Thailand ranks below the 100th mark. "In particular, the level of trust in politicians is among the lowest in the world (129th)," the report said.
Another concern is the mediocre quality of education at all levels (87th, down nine) and the still-low level of technological
readiness (65th), although Thailand shows marked improvement in this area (up 13).
The other four largest Southeast Asian economies all feature in the top half of the rankings, and all of them have made strides: Malaysia gains four places, Indonesia four, the Philippines seven, and Vietnam two.