Both models have been updated in their mid-life facelifts, bringing tweaked exteriors, more personalisation options and tech including a hands-free tailgate.
Design changes include a new front end, which is shared by both models for the first time, and '3D-effect' rear lights as standard.
Other new additions include a black two-tone roof for the five-seat C4 Picasso and a fresh range of wheels.
The facelifted cars come available in three trim levels: Touch Edition, Feel and Flair. Feel models gain standard 17in diamond-finish alloy wheels, while Flair models feature integrated roof bars and aluminium trim.
Both the C4 Picasso and Grand C4 Picasso now have a new Citroën Connect Nav system, which offers 3D, touch-operated and real-time navigation as well as voice recognition for nav, telephone and media functions and the ability to access and send texts and emails from the car.
Other tech includes hands-free tailgate operation and a number of safety systems including speed limit recognition, adaptive cruise control and active lane departure warning.
Top-spec Flair models get half leather interior trim as standard or optional full Nappa leather.
Two new engines have been added to the range. A 1.2 PureTech 110 S&S petrol with a six-speed manual gearbox, already seen on the C4 Cactus, is available on the C4 Picasso, while the option of a 1.2 PureTech 130 S&S, with a six-speed automatic gearbox, has been added to both models.