Marshall previously held roles at Agency Republic, where he was business director and marketing director, and lead the agency's BBC and Unilever accounts. He also worked on the campaign for Radio 1, for BBC World Service and the Big Brother Wap service.
In his new role, which begins at the end of this month, Marshall will head up Dialogue DLKW's digital operations on accounts such as Halifax, COI and Tena, reporting to Paul Biggins, the agency's chief executive.
Marshall said: "What excites me about this opportunity is that Dialogue DLKW is leading the charge among integrated agencies in embracing the communication paradigm shift towards digital.
"I can't wait to build an industry-leading digital team powered by a 360-degree understanding of what genuinely makes consumers tick."
Andy Hyatt has also joined Dialogue DLKW as a digital partner, charged with building the agency's HBOS digital relationship.
Andy started his career in 1995 at Lloyds TSB where he played a key role in setting up the bank's e-commerce unit. He moved to Zentropy Partners (now MRM Worldwide), where he set up a financial services centre.
Hyatt said: "The agency already produces award-winning work for HBoS and I aim to further integrate Dialogue DLKW's strategic planning and customer understanding to produce superb digital solutions for the client."
In addition, Richard Amos joins the agency as technical lead from Tribal DDB and Nick Gwyer joins as digital designer from New York's Agency.com.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .