HBO’s “True Detective” is shaping up to be the network’s most-watched rookie series since “Six Feet Under” as the first-season finale of the anthology series averaged a series-best 3.5 million viewers for its initial telecast.

“Detective” added more than 1 million viewers from last week, when it went up against the Oscars and drew 2.33 million. Across the night’s three telecasts, the series also hit a high with 4.9 million viewers.

According to HBO, with an average gross audience of 11 million viewers, “True Detective” is the network’s most popular first-year series since “Six Feet Under,” which was drawing about 11.4 million viewers per episode in its 2001 premiere season.

Sunday’s tally is impressive considering the tough live drama competition “True Detective” faced at 9 p.m. from AMC’s “The Walking Dead” and ABC’s “Resurrection,” which opened very well.

“True Detective” bowed on Jan. 12 with 2.3 million viewers for its 9 p.m. telecast, making it the premium cabler’s most-watched debut since “Boardwalk Empire” drew 4.8 million in 2010. Among the shows that “True Detective” outperformed in its premiere are dramas “Game of Thrones” (2.22 million) and “The Newsroom” (2.14 million) and comedies “Veep” (1.38 million) and “Girls” (870,000).

HBO has already renewed “True Detective” for a second season.