The finale week of NBC’s “The Voice” proved to be a good one in latenight as well for the net, with “Tonight Show” and “Late Night” hitting season highs.

According to Nielsen estimates for Dec. 17-21, “The Tonight Show with Jay Leno” averaged 1.26 million adults 18-49 and 4.06 million viewers overall — its best demo showing since early September and its largest overall audience since the February week following the net’s coverage of the Super Bowl.

And “Late Night with Jimmy Fallon” also drew its largest young-adult crowd (776,000) since early September, and hit an 18-month high in total viewers (2.03 million).

CBS’ “Late Show with David Letterman” drew 900,000 adults 18-49 and 3.09 million viewers overall, and its “Late Late Show with Craig Ferguson” drew 531,000 and 1.81 million. ABC’s “Nightline” attracted 1.08 million adults 18-49 and 3.99 million total viewers, and “Jimmy Kimmel Live” followed with 574,000 and 1.81 million total viewers.

The NBC and ABC shows were up vs. the comparable week last year, while CBS’ were down (though by just a smidge in total viewers).

Beginning Jan. 8, “Jimmy Kimmel Live” moves to 11:35 p.m., where it will compete directly with Leno and Letterman.

NBC’s ratings last week were boosted by Tuesday’s finale of “The Voice,” which wrapped just before 11 p.m. with a big 5.2 rating in adults 18-49 (6.6 million viewers in the demo) and 14.7 million viewers overall. A good chunk of that aud stuck around until 11:35 p.m. when Leno came on.

Wednesday’s “Tonight Show” featured an appearance by the show’s winner, Cassadee Pope, and Thursday’s included “Voice” judge Cee Lo Green as a musical guest.

Season to date, “Tonight Show” holds a 13% advantage over “Late Show” in 18-49 (1.05 million vs. 925,000), a reversal of a year ago when the CBS program still held a slim 1% lead.