Goodwillie is heading along the A96 to Dingwall to help bolster League Cup finalists Ross County's push for a top-six finish.
The former Dundee United striker joined Aberdeen in July 2014 and went on to score eight goals in 48 appearances at Pittodrie, but has only scored twice this season, a brace in a 3-1 win at Hearts in September.
Aberdeen have also allowed Lukas Culjak and Jamie Henry to leave the club on development loans until the end of season.
Central defender Culjak, 19, will join League One side Brechin City, while midfielder Henry, 18, has signed for League Two side Arbroath.