The contestants were announced after each category performed at Judges' Houses. There were 16 contestants (4 from each category) this year. The Live Shows were broadcast for 7 weeks from 20 October to 2 December. This year the live shows reverted to the previous format of all performances on the Saturday night and the results show on the Sunday night. However, there are 16 contestants and a reduced number of live shows, so almost all of the live result shows had double eliminations.
Nile Rodgers temporarily replaced Williams on the panel, due to touring commitments. Rodgers appeared in Williams's place from 4–18 November.
Musical guests Keala Settle and
Rak-Su, the winners of the
previous series, performed on the first live results show.
Little Mix and
Kylie Minogue performed on the second live results show.
James Arthur and
Jonas Blue,
Liam Payne and
Lennon Stella performed on the third live results show.
Michael Bublé,
Olly Murs and
Lady Leshurr performed on the fourth live results show.
Cheryl and
Tom Walker performed on the fifth live results show.
Benny Andersson and
Björn Ulvaeus appeared on the sixth live show (Andersson doing a Masterclass with the semi-finalists and Ulvaeus appearing on the judging panel alongside Williams, Field, Tomlinson and Cowell to judge the performances).
Zara Larsson performed on the sixth live results show. The live final featured a performance from
Robbie Williams (with
Take That) on the live final results show.
Final venue Unlike the previous series where the live final was held at
The ExCeL Center in London, instead this year's final was held at the normal venue which is
The SSE Arena, Wembley in London.
Winners single The winners single was the winning contestant's duet from the Sunday (2 December 2018) result show with all proceeds going to the children's charities
Together for Short Lives and
Shooting Star Chase. It is the eighth year running that the
Chancellor of the Exchequer has waived any VAT on
The X Factor's winners single. The winner was announced to be
Dalton Harris who performed a duet with
James Arthur on "
The Power of Love".
Results summary ;Colour key Act in Boys Act in Girls Act in Over 29s Act in Groups
Live show details Week 1 (20/21 October) • Theme: This is Me • Musical guests:
Keala Settle ("
This Is Me") and
Rak-Su ("
I Want You to Freak") This week's results show featured a double elimination. The three acts with the fewest votes were announced as the bottom three, and the act out of the three with the fewest public votes was then automatically eliminated. The remaining two acts then performed in the sing-off for the judges' votes. ;Judges' votes to eliminate • Field: Armstrong Martins – backed her own act, Janice Robinson, saying she deserves to be in the competition. • Tomlinson: Janice Robinson – backed his own act, Armstrong Martins. • Williams: Armstrong Martins – gave no reason but many fans accused Williams of backing his wife's act. • Cowell: Armstrong Martins – said that despite Martins being more interesting, Robinson was the better singer.
Week 2 (27/28 October) • Theme: Guilty Pleasures • Musical guests:
Little Mix ("
Woman Like Me") and
Kylie Minogue ("
A Lifetime to Repair") This week's results show featured a double elimination. Lines were frozen on Sunday at 7:30 pm, 30 minutes before the results show, and Janice Robinson was eliminated after the special guest performance from Little Mix after receiving the fewest votes. Lines then reopened and the two acts with the next fewest votes then performed in the sing-off. ;Judges' votes to eliminate • Williams: Brendan Murray – backed his own act, LMA Choir. • Tomlinson: LMA Choir – backed his own act, Brendan Murray. • Cowell: Brendan Murray – gave no reason. • Field: LMA Choir – could not decide and sent the result to deadlock. With the acts in the sing-off receiving two votes each, the result went to deadlock and reverted to the earlier public vote. LMA Choir were eliminated as the act with the fewest public votes.
Week 3 (3/4 November) • Theme: Fright Night • Musical guests:
James Arthur ("
Empty Space") and
Jonas Blue,
Liam Payne &
Lennon Stella ("
Polaroid") The live show was pre-recorded during Saturday afternoon to allow Williams to be present before flying to South America for touring commitments. Nile Rodgers appeared as a guest judge, filling in for Williams during the third results show and the fourth & fifth live shows and results shows. This week's results show featured a double elimination. Lines were originally scheduled to be frozen on Sunday at 7:30 pm, 60 minutes before the results show, the act receiving the fewest votes leaving the competition at the beginning of the show before lines would reopen and the two acts with the next fewest votes would then perform in the sing-off. However, due to a technical issue that affected the sound during Danny Tetley and Anthony Russell's performances, Saturday's public vote was cancelled and lines instead opened in the results show on Sunday. At the start of the live results show, all of the performances were shown in full before the public vote opened for 14 minutes. ;Judges' votes to eliminate • Rodgers: Molly Scott – based on the sing-off performances, effectively backing Williams' own act, Acacia & Aaliyah. • Cowell: Acacia & Aaliyah – backed his own act, Molly Scott. • Field: Molly Scott – based on the sing-off performances. • Tomlinson: Molly Scott – said both acts have potential but he was not sure Scott was "quite there yet".
Week 4 (10/11 November) • Theme: "Movies" (songs from films) • Musical guests:
Michael Bublé ("
When I Fall in Love") and
Olly Murs featuring
Lady Leshurr ("
Moves") This week's results show featured a double elimination. Lines were frozen on Sunday at 7:30 pm, 60 minutes before the results show, and Misunderstood were eliminated after the special guest performance from Bublé after receiving the fewest votes. Lines then reopened and the two acts with the next fewest votes then performed in the sing-off. ;Judges' votes to eliminate • Rodgers: Giovanni Spano – backed Williams' own act, Acacia & Aaliyah. • Field: Acacia & Aaliyah – backed her own act, Giovanni Spano, saying he brought fun and vital entertainment to the competition. • Tomlinson: Giovanni Spano – believed Acacia & Aaliyah had a future as recording artists while Spano had more of a future in musical theatre. • Cowell: Giovanni Spano – gave no specific reason but praised both acts' sing-off performances.
Week 5: Quarter-Final (17/18 November) • Theme: Big Band • Musical guests:
Tom Walker ("
Leave a Light On") and
Cheryl ("
Love Made Me Do It") This week's results show featured a double elimination. Lines were frozen on Sunday at 7:30 pm, 30 minutes before the results show, and Bella Penfold was eliminated immediately at the beginning of the show. Once that occurred, lines reopened for a few more minutes and the two acts with the next fewest votes performed in the sing off. During the results show, Cowell originally told the acts that the final six would go on
The X Factor Live Tour in 2019. After the elimination of Shan Ako, Cowell stated that he would allow both her and Penfold to join the final six on tour as well, therefore the final eight would perform on the tour. ;Judges' votes to eliminate • Cowell: Acacia & Aaliyah – backed his own act, Shan Ako. • Rodgers: Shan Ako – backed Williams' own act, Acacia & Aaliyah. • Tomlinson: Acacia & Aaliyah – based on "vocal ability" without being led by his emotions. • Field: Shan Ako – praised both acts' sing-off performances but could not decide and sent the result to deadlock, though fans accused Field of not wanting Williams to return without an act in the competition. With the acts in the sing-off receiving two votes each, the result went to deadlock and reverted to the earlier public vote. Shan Ako was eliminated as the act with the fewest public votes.
Week 6: Semi-Final (24/25 November) ;24 November • Theme: Get Me to the Final (Part I) & Mamma Mia This week's semi-final featured a triple elimination. During Saturday's show, the lines froze where the two acts with the fewest votes were immediately eliminated. They then re-opened and closed during Sunday's results show ahead of the final sing-off of the series. In addition, following all of the act's first performance during Saturday's show, each act performed a segment from an
ABBA song where
Björn Ulvaeus joined the judging panel for the performances. ;25 November • Theme: Get Me to the Final (Part II) • Musical guests:
Zara Larsson ("
Ruin My Life") ;Judges' votes to send through to the final • Cowell: Scarlett Lee – based on the sing-off performances, and said he would have made the same choice even if Scarlett Lee was not his own act; he said without her, the final would not be the same. • Williams: Acacia & Aaliyah – backed his own act, Acacia & Aaliyah. • Field: Scarlett Lee – based on the sing-off performances. • Tomlinson: Scarlett Lee – based on the vocals only in the sing-off performances.
Week 7: Final (1/2 December) ;1 December • Theme: No theme; Celebrity duets • Group Performance: "
Let Me Entertain You"/"
Rock DJ"/"
Freedom" (Top 10 contestants with
Robbie Williams) • Musical guests:
James Arthur &
Anne-Marie ("
Rewrite the Stars") and
George Ezra ("
Shotgun") ;2 December • Theme: Winners duets • Musical guests:
Pinkfong ("
Baby Shark"),
Ellie Goulding ("
Close To Me"),
Nile Rodgers &
Chic ("
Le Freak"/"
'Till The World Falls"/"
We Are Family"/"
I Want Your Love"/"
Do You Wanna Party"/"
Good Times"/"
Rapper's Delight" with Acacia & Aaliyah and Misunderstood) and
Take That ("
Shine"/"
Everything Changes" with
Robbie Williams) ==Reception==