"If I thought I had done something wrong I would have resigned in December," he told senators.
"I didn't resign then and I'm not resigning now because I have done nothing wrong."
He says he is the victim of a political vendetta.
Impeachment prosecutor David Ellis, in his rebuttal, emphasised that Mr Blagojevich had refused to appear under oath to answer questions, opting instead to make a closing speech.
In his closing remarks, Mr Ellis said: "The evidence showed that throughout his tenure as governor, the governor has abused the power of his office and put his own interest above the interest of the people."
The impeachment followed an investigation by a 21-member committee of Illinois legislators, which looked at testimony from FBI agents who wiretapped phone calls to and from the governor's office about who should fill President Obama's seat.
It is alleged the conversations show that Mr Blagojevich was trying to use the seat to get himself or his wife a job.
Mr Blagojevich is the first US governor to be impeached in more than 20 years, after Arizona's Governor Evan Mecham was removed from office in 1988.
Four of Illinois' past eight governors have faced criminal charges and Mr Blagojevich's predecessor, George Ryan, is currently serving a jail sentence for corruption.
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