The document was signed at a meeting of the WTO General Council in Geneva by President Viktor Yushchenko and the global trade body's secretary general, Pascal Lamy.
Ukraine is set to ratify the agreement by July 4, and will become a full-fledged member 30 days after ratification.
Yushchenko told the meeting that Ukraine will not attempt to block Russia's admission to the organization.
"We completely support Russia's WTO accession bid. Ukraine will do all it can to facilitate Russia's early admission," he said.
After 14 years of accession negotiations, the Working Party on the Accession of Ukraine successfully adopted Ukraine's 'accession package' in late January. Prime Minister Yulia Tymoshenko said a few days later that her country expected to become a "full-fledged WTO member" on February 7.
Yushchenko earlier cited economic experts as saying that that accession would add an additional 1.5-1.7 points to the country's annual GDP growth.
However, many politicians fear WTO membership could have negative consequences for national industries. Viktor Yanukovych, opposition leader and former prime minister, said domestic agriculture, as well as the car making, shipbuilding and defense sectors, could be the hardest hit.
Kiev also plans to launch negotiations on February 18 with the EU on establishing a free trade zone.
A source in the Russian delegation of negotiators said that if Moscow fails to join the WTO before Kiev, Russia's accession could be put off indefinitely. Russian authorities still expects expect the country to join the WTO by mid-summer.
Russian Finance Minister Alexei Kudrin told the recent World Economic Forum in the Swiss ski resort of Davos that Ukraine was seeking to enter the WTO on unfavorable terms simply to beat Russia to it and gain a negotiating advantage over Moscow.