Oracle has previously worked with several agencies, including Gyro, but it is understood to have slimmed down its roster, with Gyro taking the bulk of the work.
The integrated agency, which specialises in B2B DM, has carried out various campaigns for Oracle, including design, lead generation and fulfilment work.
Activity created by Gyro earlier this year focused on promoting an IT 'health-check' to small firms by sending 60,000 communications to decision-makers in the UK and Ireland.
Founded in the late 70s, Oracle is the world's largest enterprise software company. Since January it has acquired eight firms, most recently Telephony@Work, a provider of internet protocol-based contact-centre software.
Gyro's clients include Tate & Lyle, Moss Bros and Rentokill Initial.
In April, the London-based agency came 16th in a survey of the fastest-growing companies in the UK.