Ubogagu, who narrowly missed the cut for the England squad that went on to finish fourth at this year’s Women’s World Cup in France, is Tacon’s seventh international signing of 2019.
The 26-year-old joins Swedish stars Kosovare Asllani and Sofia Jakobsson in making the high profile switch to the Spanish capital. Brazilian defenders Daiane Limeira and Thaisa have also arrived in Madrid, as has Paraguayan forward Jessica Martinez.
French defender Aurelie Kaci has moved across Madrid from Spanish champions Atletico.
Ubogagu may have missed the cut for the World Cup, but she was part of the England squad that won the SheBelieves Cup ahead of the United States earlier this year.
The player, who was born in London but raised in the United States from an early age, has spent most of her club career to date on American soil, barring a short spell with Arsenal in 2014 after a collegiate career at Stanford University, a 2018/19 loan in Australia.
Ubogagu had been with Orlando Pride since 2017, where she counted global superstars like Alex Morgan and Marta among her teammates.
Newly promoted to Spain’s top flight, Tacon will play home games at Real Madrid’s training ground this season and complete the full transition into Los Blancos’ first ever women’s team at the end of the campaign.