The 28-year-old joined the U's from Rotherham United in February of 2016 after an initial six-week loan spell.
Maguire, who has played for Scotland twice, scored 17 goals in 54 appearances for Oxford last season.
"He had many offers to consider so we are delighted he has chosen us," boss Lee Clark told the club website.
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Bury have signed Scotland international striker Chris Maguire from fellow League One side Oxford United on a two-year contract.