The final Poirot episode attracted 4.86 million (21.6%) on Wednesday evening, according to overnight figures.
David Suchet's last appearance as Hercule Poirot gained back over 600,000 viewers from last week on ITV at 9pm, with an added 311k (1.6%) watching on +1.
On BBC One, DIY SOS interested 4.60m (20.1%) at 8pm, followed by Britain on the Fiddle with 4.04m (18.2%) at 9pm.
BBC Two's MasterChef: The Professionals gathered 2.80m (12.2%) at 8pm, while Tudor Monastery Farm appealed to 1.56m (7.0%) at 9pm.
On Channel 4, Grand Designs was seen by 1.44m (6.3%) at 8pm (349k/1.6% on +1), followed by the return of 24 Hours in A&E with 2.06m (9.3%) at 9pm (444k/2.7%). Gogglebox amused 1.54m (9.0%) at 10pm (297k/1.3%).
Channel 5's Animal Clinic with Ben Fogle brought in 719k (3.2%) at 8pm. JFK's Secret Killer intrigued 1.33m (6.0%) at 9pm (142k/0.8%).
On ITV2, the latest TOWIE entertained 690k (4.0%) at 10pm (114k/1.2%).
