After 12 years of tough on-off negotiations, a WTO working party which has overseen the talks in Geneva looks certain to approve the final terms under which the kingdom will enter, probably within the next six weeks.
Entry is expected to boost foreign investment in the country, providing funds for diversification of the largely oil-based economy, and bring new export opportunities for Saudi firms, especially in the petrochemical industry.
Investment has already become less cumbersome and fewer sectors are restricted to local businesses, Samba Financial Group economist John Sfakianakis said in a report this week.
"Adherence to international property rights has improved and the liberalisation of the insurance market is improving," he said.
Admission still has to be agreed by the WTO's ruling General Council in early November, but that is seen as a formality and will clear the way for Saudi Arabia to attend a key ministerial meeting in Hong Kong in December as a full member.
The talks have dragged on partly because of domestic fears that WTO free trading rules would limit the country's right to restrict imports of goods prohibited under Islam, including pork, alcohol or what it regards as pornography.
The kingdom is expected to record a budget surplus of up to 200 billion riyals ($53 billion) this year on record world prices for its crude exports, but is trying to ease dependence on oil and create jobs for a fast-growing population.