Arkhom, 64, was a transport minister in the government put in place after a 2014 coup, and was former head of the state planning agency, where he worked for more than three decades.
He replaces banker Predee Daochai, who unexpectedly quit on Sept. 1 after only a few weeks.
Arkhom holds a master's degree in Development Economics from Williams College in the United States. He has also served on the Bank of Thailand's Monetary Policy Committee and the country's Board of Investment.
The new minister should help build confidence and continue government policy with billions of dollars of stimulus measures being rolled out, analysts said.
Arkhom's experiences "should equate to a seasoned hand with regards to economics from both the theoretical and practical aspects," said Kobsidthi Silpachai, head of capital markets research of Kasikornbank.
Visit Limluecha, president of the Thai Food Processors' Association, said Arkhom should be able to "work with the political side and withstand political pressure".
Thailand's economy suffered its biggest shrinkage in 22 years in the second quarter and the central bank expects a record 7.8% economic contraction this year.
Though Thailand has so far reported only 3,590 coronavirus infectionshttps://tmsnrt.rs/3cYUtF2 and has lifted most restrictions, its tourism-reliant economy has been badly hit, with foreign visitors absent since April due to an ongoing travel ban.
The government expects just 6.7 million foreign arrivals this year compared to last year's record 39.8 million visitors, whose spending made up about 11.4% of gross domestic product.
(Reporting by Orathai Sriring and Satawasin Staporncharnchai; Editing by Martin Petty)
By Orathai Sriring and Satawasin Staporncharnchai