Let It Shine premiered to an audience of 6.3 million viewers between 7PM and 8:25PM the previous Saturday but this week dipped by a million viewers to 5.3 million, peaking with 5.7 million towards at 8PM.
The Voice UK, which used to air on BBC One, made its debut on ITV for series six with its least watched launch to date last Saturday night.
An average of 6 million viewers (including ITV+1) tuned in between 8PM and 9:35PM for the first show and this dropped to 5.5 million for this weekend's second episode, peaking with 6.3 million.
While The Voice UK claimed victory over Let It Shine on the night, the show remained significantly down year-on-year by around a million viewers.
Earlier in the evening on BBC One, Pointless had 5 million viewers - down 300,000 on last week - while ITV's Ninja Warrior UK also fell 300,000 viewers to 3.1 million.
Casualty was up on BBC One to 4.8 million viewers (from 4.6 million) whereas new drama Taboo continued with 4.1 million viewers, down 700,000 on the first episode.
Over on ITV, Through the Keyhole with Keith Lemon had 3.4 million viewers, up an impressive 500,000 week-on-week.
Elsewhere, in a much later than usual time slot, Celebrity Big Brother's latest highlights on Channel 5 at 10:30PM had 1.4 million viewers.