Viktoria Mamontova was sentenced to death after police found more than one kilogram (2.2 pounds) of heroin in her hotel room in Bangkok in 2000. The sentence was later commuted to 27 years in prison.
"I am sure that a positive resolution of this issue will once again demonstrate your great wisdom and adherence to the high principles of humanism, Your Majesty, as well as the mutual confidence and respect that characterize relations between our countries," President Viktor Yushchenko said in his letter.
In an attempt to obtain Mamontova's release and repatriation, Ombudsman Nina Karpacheva earlier visited her in prison, reporting that she regrets her crime and has tried to atone for her guilt with exemplary conduct and good work.
Mamantova's elderly mother is waiting for her daughter in Ukraine.