HBO’s “Boardwalk Empire” was down in the ratings this fall — another victim of the monster that is AMC’s “The Walking Dead” — but closed on Sunday with a 10-week high.

According to Nielsen estimates, the 9 p.m. airing of “Boardwalk Empire” averaged 2.18 million viewers, up about 200,000 from the previous week and the show’s largest audience since Sept. 15. Still, it was off about 20% from last year. It was an especially brutal night competition wise, including the big Patriots-Broncos NFL game, “Walking Dead” and the American Music Awards.

“Boardwalk,” which has been renewed for a fifth season, has generally trended down in the ratings since its big first year. That first-season finale wrapped in December 2010 with 3.29 million same-night viewers, with the 2011 closer drawing 3.01 million and last year’s slipping to 2.73 million.

By comparison to other recent season finales of HBO dramas, Sunday’s closer of “Boardwalk Empire” came in above “The Newsroom” (1.5 million) but behind “Game of Thrones” (5.4 million) and “True Blood” (4.1 million).

Episodes of “Boardwalk Empire” have been gaining a little over 1 million viewers with a full week’s worth of DVR playback, going from nearly 2 million to about 3 million in L7. According to HBO, the gross audience for the show across various platforms this season is about 7 million.

Following “Boardwalk Empire” on Sunday, comedy “Getting On” drew 520,000 viewers for its premiere.