The character was introduced in the season nine premiere episode, "Nice to Meet You, Walden Schmidt" to replace the character of Charlie Harper after actor Charlie Sheen was fired from the series.Walden was a main character throughout the show's final four seasons (seasons 9-12).He is listed on Forbes' fictional list of the top 15 richest characters as number 11, with a wealth of approximately .3 billion.
Over the course of his duration on the series, Walden's personality greatly matured.
For the first eight seasons of Two and a Half Men, the series' main character was Charlie Harper, portrayed by actor Charlie Sheen.
In February 2011, after continued verbal attacks against series creator Chuck Lorre by Sheen, CBS announced that Two and a Half Men would suspend production for the rest of its eighth season.
In April 2011, Chuck Lorre announced that he had developed an idea for a Two and a Half Men reboot that would exclude Sheen and have Jon Cryer, who portrayed Alan Harper, in a lead role alongside a new character.
He's actually a smart guy, so they tried to come up with a different take on a character for him, and it's been fun to watch him figure out who this guy is." In the season nine premiere it is revealed that Charlie Harper has died in France and has left his beach house to his brother Alan.
However, Alan has to put the house up for sale as he is unable to afford the mortgage payments and property tax.While Alan is speaking with Charlie's ashes and trying to decide where to spread them, Walden suddenly appears on the house's back deck, scaring Alan and causing him to drop the ashes on the living room floor.Lorre was originally fixated on a character in his mid to late forties and originally approached Hugh Grant, who was fifty at the time.However, meeting 33-year-old Kutcher changed his mind.Lorre was quoted as saying "It got easy to let go once I met with Ashton.Because this was an opportunity to work with a pretty big talent, and it just became apparent to figure it out and let go of the old idea." Jon Cryer stated in 2014 that "the writers didn't want to just do Kelso from 'That '70s Show,' because that's a criminal waste of Ashton's intelligence.