Tymoshenko is serving a seven-year prison sentence after being convicted on charges she abused her authority in helping to broker a natural gas deal with Russian company Gazprom in 2009. European leaders have expressed concern about her detention, saying the charges appear to be politically motivated.
In an open letter to Ukrainian President Viktor Yanukovych, the former prime minister and opposition leader said she was embarking on a campaign of civil disobedience.
"So as to reduce public fear of your regime, so as to once again say that you're humiliating and destroying Ukraine, I am starting a personal campaign of civil disobedience," Tymoshenko's letter read.
Ukraine's formal association talks with the European Union were suspended following the sentencing of Tymoshenko.
"From this moment on I no longer recognize your prosecutors and investigators," her letter read.
October elections in Ukraine left the ruling Party of Regions in power, though Tymoshenko's opposition Fatherland Party was a close second.
European observers expressed concern about the "abuse of power" during the election. The European Parliament said Ukraine failed to pass "a key test" during the contest.