Boyd began his career in the SPL with Kilmarnock, scoring 63 times in 153 league appearances from 2000 to 2006. In January 2006, when he joined Rangers for a transfer fee of £500,000. There, he got off to a flying start by scoring a hat-trick in his debut, a 5-0 win over Peterhead in the third round of the Scottish Cup.
By the time Dundee United arrived at Ibrox in December 2009, Boyd had won one SPL title (2008-09), one Scottish League Cup (2007-08) and back-to-back Scottish Cups (2007-08, 2008-09). He was also sitting on a total of 155 league goals, three behind the SPL record of 158, set by Celtic's Henrik Larsson from 1997 to 2004.
He matched the record before the half-hour mark, starting with a penalty kick in the 20th minute, followed by a long-range effort four minutes later, then a tap-in finish in the 29th minute. He went through a relatively quiet period until deep into the second half before finally breaking Larsson's record with a fourth goal in the 75th minute, then adding another for good measure in the 80th minute. One minute later, manager Walter Smith substituted him and he exited to a massive ovation from the home supporters. Rangers won 7-1.
Boyd left Rangers at the end of the season after collecting another league title and a Scottish League Cup, and increasing the SPL goal record to 164. After spending time in England, Turkey, and the United States, he returned to Rangers in 2014, though they were in the Championship at the time. In 2015, he returned to the SPL with Kilmarnock, his current club, and has since increased his record to 172.