In 1994, Jack in the Box advertising brought back their longtime clown mascot Jack, reimagined as a businessman regaining his position as CEO of the company, after having been "fired" in an earlier 1980s campaign. The idea was the brainchild of ad executive Rick Sittig. The campaign was highly successful, and is credited with reiventing the company after the 1993 E. coli outbreak. Sittig would voice Jack and direct every commercial in the campaign for the next 20 years. In 1997, Sittig founded his own agency Kowloon Wholesale Seafood Co. (later renamed Secret Weapon Marketing), and initially Jack in the Box was its sole account. A 2008 Adweek profile of Sittig described him as "the font of Jack’s continuity." 
In August 2015, Jack in the Box severed ties with Sittig and Secret Weapon Marketing in favor of the agency David & Goliath.  According to Jack in the Box, this was in part because the irony that had been a trademark of the company's advertising "no longer jibes with the culture or the chain's more recent focus on quality."
The first post-Sittig commercial was New Journey, directed by Breaking Bad creator Vince Gilligan, heralding a series of commercials wherein Jack Box goes on a "heroic but silent quest for better ingredients and better burgers." Jack, who had been previously voiced by Sittig, did not talk in the commercials until 2016's Undercover Jack.
Changes from the Sittig era
Prior to the soft reboot, commercials in the early 2010s were characterized by a somewhat ribald tone, including sly allusions to erections, sexting, and sexual harassment, which may have played a role in Jack in the Box's decision to cease advertising with Sittig and Secret Weapon Marketing. In contrast, commercials in the post-Sittig era have tended to be more wholesome and safe, with less emphasis on humor. A notable exception is 2018's Jack's Bowls, which was met with controversy.
As a result of the change, Rick Sittig was replaced as Jack's voice actor. David & Goliath's first series of commercials featured Jack in a silent role, perhaps so that the change would not be perceptible to the general audience. When questioned about Jack's silence for a January 2016 Fast Company article, a company representative stated "Jack's quiet at the moment, but that's a product of the role he’s been playing and the recent journey he's been on." However, the eventual recasting did not go unnoticed: one internet commenter observed the new actor "talks with a stuffy nose it seems like,", while comedian Paul F. Tompkins tweeted "Hey Jack In The Box: I know it's a different guy doing the clown voice. You think you can fool me? I'm watching you."
In a 2016 blog post about redesigning the Jack in the Box website, Matt Anderson, CEO/ECD of the ad agency Struck, wrote, "Over the last year or so, the Jack in the Box brand has evolved. Part of that evolution has been with the character of Jack [...] You may have noticed that Jack is more of an explorer and less of a goofball uncle."
For the most part, advertising in the post-Sittig era has retained the Jack Box continuity established in 1994. However, carelessness with the previously-established canon and a lack of cohesive worldbuilding have left the canonicity of several elements in flux.
Jack's family appears to have been de-emphasized. Jack's son Jack, Jr. has yet to make an actual appearance in a commercial since the soft reboot began. Among the scant indications he still exists are a framed picture of him seen in Cricket's Cravings and a mention in a Reddit thread. Extended members of the Box family have yet to be seen.
In October 2016, it was announced Jack and his wife Cricket were expecting a child as part of an ad campaign for Brunchfast. However, there was never a follow-up campaign about the presumed birth. Jack mentioned an unnamed daughter in a November 2018 tweet, but it is unclear if she is the result of Cricket's 2016/2017 pregnancy, a previously-unseen older child retconned into existence, or a mistake by the social media team.
Laureenne Sala, a copywriter who worked wih Secret Weapon Marketing, made this observation on Quora:
One thing that others might not notice is that when Dick’s agency was writing the commercials, they were aware of Jack’s entire world. The same woman played Jack’s wife. The same kid played Jack’s son. There were rules about Jack’s mouth, his career, his family life, and how his face could change. The new agency doesn’t follow those, but nobody probably notices.
- Jack's Back (1994)
- Dawson, Angela. Kowloon’s Seafood Platter. Adweek. August 10, 1998.
- Solman, Gregory. Dick Sittig, in Situ. Adweek. December 1, 2008.
- Bell, Diane. 'Jack,' of Jack in the Box, pops the "B" news. San Diego Union-Tribune. October 6, 2016.
- Peters, Bill. What Jack In The Box, 'Hunger Games' And 'Seinfeld' Have In Common. Investor's Business Daily. May 26, 2016.
- Jack Visits (2010)
- Texting (2013)
- Company Picnic (2014)
- Ungerleider, Neal. This Is How Jack In The Box Is Overhauling Its Menu. Fast Company. January 21, 2016.
- _ders. Reddit comment. Reddit. January 22, 2018.
- Tompkins, Paul F. "Hey Jack In The Box: I know it's a different guy doing the clown voice. You think you can fool me? I'm watching you." Twitter. May 15, 2017.
- Anderson, Matt. Tear It Down, Build It Back Up. Experience Affinity. April 6, 2016.
- therealjackbox. "Jack Jr. is my son. I made him with my wife, Cricket." Hey Reddit - Jack here, from Jack in the Box, ready to answer all your questions about my tacos, curly fries, hat size, you name it. I'll be posting at 10 AM PST every day from now till 5/11 (that's right, a whole week). So let’s do this. AMA! Reddit. May 11, 2018.
- "I always say to my daughter 'It's not how many times you fall it's how many times you take advantage of reasonable delivery prices once you're on the ground.'" - Jack Box on Twitter. November 27, 2018.
- Sala, Laurenne. Why did Jack-In-the-Box change the voice of Jack in their commercials? Quora. April 14, 2017.