The agency has hired Kenneth MacKenzie as account director and Lauren Agnew as web developer.
MacKenzie joins from The Zen Agency and was previously head of digital at Picardy, while Agnew has been recruited from S1.com.
The appointments and new business come as 999 Design plans to treble its digital design turnover over during the next year with through investment. In addition to the services it already offers, 999 will begin to provide internal communications, intranets and extranets plus "effective" ecommerce systems.
The company reported turnover of £3.6m for the last financial year and expects to see a growth of more than 200% in its digital work over the next 12 months.
Aileen Geraghty, managing director of 999's London office, said: "999 has always offered a digital design function but we have predominantly focused on the brand side.
"Although this is an area we excel at, the appointment of Kenneth and Lauren significantly strengthens our offering across a wider range of digital marketing services."
Asperity Employee Benefits has appointed 999 Design to help develop improved communication with its various audiences.
Asperity's Reward Gateway product claims to be the leading staff discount scheme in the UK employee benefits market, servicing more than 850,000 employees with discounts at more than 1,300 retailers including John Lewis, M&S and Boots.
An initial project has seen 999 create a Reward Gateway brochure, which Asperity will distribute to prospective new clients, as well as an advertising wrap for the cover of trade magazine Employee Benefits and consulting services on messaging and digital marketing.
999's London office is leading the account, with both parties currently discussing a number of projects to be rolled out over the next 12 months, including a refresh of Asperity's range of marketing, sales and employee communication material.
Glenn Elliot, managing director of Asperity, said: "Their understanding of our ethos and creative approach to communicating key messages to our audiences, both internal and external, put them head and shoulders above everyone else.
"There are a number of projects in the pipeline with 999 and we look forward to forging a productive relationship in the months ahead."
999 Design has three offices in London, Manchester and Glasgow and its clients include the BBC, BT, the NHS and Warburtons.