The comic actor and author plays Tommy Beresford to Jessica Raine's Tuppence Beresford in a six-part period drama based on two novels by Agatha Christie.
"I like that Tommy has to defer to her; that she is more intelligent and heroic than he is," Walliams went on.
Partners in Crime is scheduled to air on BBC One at the end of July.
The drama, screened to reporters in London on Monday, forms part of a series of BBC programmes marking the 125th anniversary of Christie's birth.
Tommy and Tuppence have not been seen on British TV since the 1980s, in which they were played, on ITV, by James Warwick and Francesca Annis.
The characters went on to spawn a trio of French films, starring Andre Dussollier and Catherine Frot, that renamed the characters Belisaire and Prudence.
The sleuthing duo also appeared in a 2006 edition of the Marple TV series, in which they were played by Anthony Andrews and Greta Scacchi.
"These characters have not been done for a while and I thought it would be a good opportunity to do a new version," said Walliams on Monday.
"Something about having a husband and wife detective duo really appealed," he went on. "I don't think there's been one since Hart to Hart."
Hart to Hart, which ran from 1979 to 1984 before being revived in the 1990s, starred Robert Wagner and Stefanie Powers as a pair of wealthy married sleuths.
Call the Midwife star Raine described her character as "forward-looking and modern". "It's so nice to play a woman who isn't put-upon or a victim," she continued.
"I like how front-footed and quick-witted she is. She's quite funny and intelligent and curious, all these things you want to be in real life."
Raine, whose other recent drama credits include Wolf Hall and Fortitude, said she also enjoyed the physical nature of the role.
"I got to do some great stunts - to smash windows and climb through windows and have a full-on fist fight with another woman," she explained.
In contrast, joked Walliams, his more passive part in proceedings found him more often seen "busy helping myself to some biscuits".
More Clouseau than Poirot, Tommy Beresford is depicted as a well-meaning but ineffectual man whose lofty plans have yet to yield results.
"Tommy's a good man but he's let his ambitions slide," explained Walliams. "He needs Tuppence to help him make something of his life."
The couple are introduced in the first half of the series, based on Christie's 1922 novel The Secret Adversary, as a bickering couple who are often at odds.
"But there's a real love underneath the bickering, and over the course of the series they re-find that love," said Raine, who described her on-screen relationship with Walliams as "funny and zesty and fresh".
Both Walliams and Raine expressed a willingness to return to their roles, though the former pointed out there are only so many novels and stories to adapt.
"There are only five Tommy and Tuppence books" - four novels and a collection of short stories - "so we would have to invent a few more," he explained.
A three-part adaptation of And Then There Were None, Christie's most-read book, is also being made to mark the anniversary of Agatha Christie's birth.
Best known for his Little Britain partnership with Matt Lucas, Walliams is also a successful children's author and a judge on Britain's Got Talent.
Little Britain star David Walliams has described his new role as one half of a husband and wife detective duo as "the damsel in distress" of the partnership.