The couple made an announcement in the 'Births, Marriages and Deaths' section of a leading daily today, reported Digital Spy.
"The engagement is announced between Christian, son of Mr and Mrs GM Horner and Geraldine, daughter of the late Mr LF Halliwell and Mrs A Parkinson," the notice reads.
A spokesperson for the 42-year-old Spice Girls star added, "Everyone is really pleased for them and wish them happiness and good health together for many, many years to come."
The pair have been friends since 2009 and officially confirmed their relationship earlier in 2014.