A New York judge said Michael Cohen deserved a harsh punishment for crimes including tax evasion, lying to Congress and arranging illegal payments to silence women who posed a risk to Mr Trump’s presidential campaign.
District Judge William H Pauley III rejected arguments by Cohen’s lawyers that he should be spared jail because he co-operated in multiple federal investigations involving Mr Trump.
Cohen said his “blind loyalty” to Mr Trump made him feel a duty to “cover up” the president’s “dirty deeds”.
Cohen’s crimes included evading $US1.4 million dollars (£1.1m) in taxes and misleading Congress about his talks with Russians about a Trump skyscraper project in Moscow.
Mr Trump had called for a tough sentence for Cohen, whom he labelled a liar.
The judge said Cohen’s co-operation with prosecutors “does not wipe the slate clean” of his crimes.
Mr Pauley said Cohen “appears to have lost his moral compass” and the lawyer “should have known better” than to dodge taxes, lie to Congress and violate campaign finance laws.
After the case, an adviser to Cohen said the former political fixer will “state publicly all he knows” about Mr Trump after special counsel Robert Mueller completes his investigation.
Lanny Davis said that Cohen “continues to tell the truth about Donald Trump’s misconduct over the years”.
Davis, who was previously a lawyer for Cohen, said he will assist him in testifying before any Congressional committee “interested in the search for truth and the difference between facts and lies”.
Cohen has been ordered to hand himself in on 6 March to start his sentence.