With an assist from the season finale of “The Voice,” NBC’s “Tonight Show Starring Jimmy Fallon” has hit a six-month ratings high — beating its Jimmy Kimmel-David Letterman competition combined in the key young adults demo.

Nielsen estimates that “Tonight” averaged a 1.16 rating in adults 18-49 for the week of Dec. 15-19, the show’s highest rating since the week of June 9-13. Its peak night (1.51 rating) came on Tuesday following the Peacock’s coverage of the “Voice” finale with an episode that featured an appearance by Justin Timberlake and guests Christoph Waltz and Nicki Minaj.

The 1.51 was the best for the show since a May 22 episode (on the night of the “Last Comic Standing” season premiere) when guests included Will Ferrell performing with Red Hot Chili Peppers drummer Chad Smith, a Ferrell look-alike.

“Tonight Show” was up 15% in rating vs. the comparable frame of 2013 with Jay Leno as host (1.01) to beat the combined demo scores of ABC’s “Jimmy Kimmel Live” (0.57, down 23% from last year) and CBS’ “Late Show With David Letterman” (0.55, down 14% from last year).

In total viewers, “Tonight” (4.218 million) had its best week in three months and easily beat both “Late Show” (2.791 million) and “Kimmel” (2.539 million).

In the 12:35 a.m. hour, NBC’s “Late Night With Seth Meyers” beat the final week of CBS’ “Late Late Show With Craig Ferguson” by a 32% margin in 18-49 (0.50 vs. 0.38), winning all five nights. Ferguson pulled ahead in total viewers (1.733 million vs. 1.637 million).