Smithwick has taken the decision to leave the show and will depart next Friday (October 5).
A Lime Pictures spokesperson told Digital Spy today (September 29): "After 18 months on Hollyoaks, series producer Emma Smithwick will be stepping down. Executive producers Bryan Kirkwood and Tony Wood will continue to oversee the show.
"We thank Emma for all her hard work on Hollyoaks and wish her every continued success for the future."
Meanwhile, Smithwick commented: "It has been an extraordinary 18 months on Hollyoaks, and I have been very fortunate to work with some of the most dedicated teams in the business - from cast and crew to the writers and brilliant editorial team.
"I have also had the pleasure of working with the hugely talented and capable Bryan Kirkwood, so I know that I will be leaving the show in great hands. I am so excited for the future of the show and want to thank everybody at Lime for making my time on Hollyoaks very special."
Smithwick joined Hollyoaks as series editor in spring 2011, before later being promoted to the position of series producer.
George Smith's homelessness storyline, Lynsey Nolan's shock murder, the return of Silas Blissett, and Brendan Brady's explosive feud with Walker are among the high-profile storylines which have appeared on screen during her stint at the top. Smithwick was also an executive producer of the most recent Hollyoaks Later series.
Smithwick is credited for working on growing and engaging with the show's younger audience with projects including E4 specials, the Wretch 32 stage invasion and the Savage Party event featuring Maverick Sabre.
Kirkwood, who previously produced Hollyoaks for three years until 2009, returned to Lime Pictures in April after stepping down as executive producer of EastEnders.