Income for the period was $115m, or $1 per share, a 40% fall.
The operator’s financial report shows total adjusted EBITDAR for the year was $681.3m, a 14% rise.
For 2019, the company projects adjusted EBITDAR of between $885m and $910m.
In the fourth quarter of 2018, revenues were $791.6m, up 33% year-on-year.
Boyd Gaming reported net income of $22.9m, or $0.2 per share, for Q4, almost four times less than in Q4 2017.
Total adjusted EBITDAR for the quarter was $208.6m, an increase of 41%.
Keith Smith, Boyd Gaming President and CEO, said: "The strategic initiatives we have executed over the past several years continued to pay off in the fourth quarter of 2018. Our recent acquisitions, efficiency programs and marketing refinements all contributed to strong results.
"We delivered revenue, adjusted EBITDAR and margin growth in every segment of our business in the fourth quarter as well as the full year. Our consumer remains healthy and we believe we are in a solid position to continue creating value for shareholders in 2019 and beyond."
