The Black Eyed Peas star has been on the show since the first series in 2012, when it aired on the BBC.
But he's suggested that 2018 could be his last run.
Will, who has already been confirmed for The Voice Kids in the summer, made the comments ahead of Saturday's final.
“I don’t know," Will replied when asked if he'd return.
Will told the Daily Mirror newspaper: “I have to really take a deep breath, go in a quiet room, meditate and think about what I should be doing.”
Will's act Donel Mangena finished runner up in The Voice UK final results, but Will is confident he has a bright future.
Comparing the teenager to Michael Jackson, Will said: "The way he is in the studio, how attentive he is, mentally, spiritually, his excitement and dedication. That’s what Michael was like.”
Meanwhile, Olly Murs has said he hopes to return to The Voice UK in 2019 following his debut this year.
“We’ve had initial talks with ITV,” he said. “They’ve said they’d love me to come back – I’d love to come back. So until it’s all signed, sealed, delivered – we’ll see. But without a doubt I’d love to stay and come back.
“I can’t wait to do it again,” he added. “I hope I come back for many years.”
The Voice UK has already been confirmed for 2019 with applications already open to audition
Alongside Will and Olly, Sir Tom Jones and Jennifer Hudson were coaches on this year's series, which was again hosted by Emma Willis.