In 2015, Ifans starred with Jennifer Aniston in She's Funny That Way, directed by Peter Bogdanovich.

Since 2007, Ifans has sung with the psychedelic rock band The Peth (peth is Welsh for "thing"), featuring Super Furry Animals' Dafydd Ieuan, which played a number of concert dates in south Wales and in London in the autumn of 2008.

He played Xenophillius Lovegood, editor of the wizarding magazine The Quibbler and father of the eccentric Luna Lovegood.

In the same interview, he also announced that he would play the title role in the film Mr. He played a villain in Nanny Mc Phee and the Big Bang, which also starred Emma Thompson and Maggie Gyllenhaal.

He played Adrian, the pompous eldest brother in Little Nicky (2000).

Other film roles include: Eyeball Paul in Kevin and Perry Go Large (2000), Nigel in The Replacements (2000), Iki in The 51st State (2001), William Dobbin in Vanity Fair (2004), and Vladis Grutas in Hannibal Rising (2007).