The 31-year-old has joined Madrid CFF on a six-month deal after a decade in Sweden, where she scored 60 goals, with Umea IK and Kristianstad.
She joins compatriot Chidinma Okeke at the Spanish Primera Iberdrola side.
Reacting to the deal Chikwelu said: “This is a different and competitive league, as a footballer you want to test yourself around the best players.
“The Spanish league is an interesting place for African players and I believe this will continue to help develop our players’ game and their profile.”
Chikwelu captained Nigeria to two Africa Women’s Championship victories in 2016 and 2018.
She also played a key role at last year’s Women’s World Cup as the West Africans reached the knockout stage for the first time since 1999.
Another compatriot, the four-time African footballer of the year winner, Asisat Oshoala is the biggest African name in the 16-team league with FC Barcelona.
Many African players have enjoyed huge financial incentives in China and savoured the competitive nature with its top clubs always on the hunt for new players.
But the fast-growing Spanish league also presents African players with a good platform to parade their skills.
Barcelona – Asisat Oshoala (Nigeria)
CD Tacon – Osinachi Ohale (Nigeria)
EdF Logrono – Ida Guehai (Ivory Coast), Barbra Banda (Zambia), Grace Asantewaa (Ghana) Jade Boho (Equatorial Guinea)
Madrid CFF – Rita Chikwelu and Chidinma Okeke (Both Nigeria)
Rayo Vallecano Femenino – Priscilla Okyere (Ghana)
Real Betis Feminas – Michaela Abam (Cameroon)
Sevilla FC – Toni Payne (Nigeria)
Sporting de Huelva – Peace Efih (Nigeria) Princella Adubea (Ghana)
UD Granadilla Tenerife – Ange N’Guessan (Ivory Coast) Raissa Feudijoat (Cameroon)
Valencia – Zenatha Goeieman (Namibia)