Pada 3121 Januari 20132015 yang bener dek, Casemiro dipinjamkan ke [[Real Madrid]] di Spanyol, ditugaskan ke [[Real Madrid Castilla|tim B]] di [[Segunda División]].<ref>{{cite news |url=http://www.lancenet.com.br/futebol/Paulo-empresta-Casemiro-Real-Madrid_0_857314458.html |title=São Paulo empresta Casemiro ao Real Madrid, e volante começará no time B|trans-title=São Paulo loan Casemiro to Real Madrid, and holding midfielder will start in B-team |newspaper=Lance! |language=pt |date=31 January 2013|access-date=19 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20131219093919/http://www.lancenet.com.br/futebol/Paulo-empresta-Casemiro-Real-Madrid_0_857314458.html|archive-date=19 December 2013}}</ref> Dia memainkan pertandingan pertamanya di kompetisi pada 16 Februari, dimulai dengan kekalahan 1–3 di [[CE Sabadell FC]].<ref>{{cite news |url=http://www.mundodeportivo.com/20130216/futbol/liga-segunda-division/anibal-lidera-victoria-sabadell-ante-castilla_54365470706.html |title=3–1: Aníbal lidera la victoria del Sabadell ante el Castilla|trans-title=3–1: Aníbal leads Sabadell win against Castilla |newspaper=Mundo Deportivo |location=Barcelona |language=es |date=16 February 2013|access-date=19 December 2013}}</ref> Casemiro melakukan debutnya di La Liga pada 20 April, bermain selama 90 menit penuh dalam kemenangan kandang 3-1 atas [[Real Betis]].<ref>{{cite web |url=http://espnfc.com/en/report/348223/report.html?soccernet=true&cc=null |title=Ozil at the double for faltering Real |website=ESPN FC |date=20 April 2013|access-date=19 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20140101072726/http://espnfc.com/en/report/348223/report.html?soccernet=true&cc=null|archive-date=1 January 2014}}</ref> Pada tanggal 2 Juni, dia mencetak gol pertamanya di Eropa, membuka kemenangan 4-0 tim cadangan atas [[AD Alcorcón]] di [[Stadion Alfredo Di Stéfano]].<ref>{{cite news |url=http://www.marca.com/2013/06/02/futbol/2adivision/1370196056.html |title=Fiesta de graduación del Castilla que complica al Alcorcon|trans-title=Castilla graduation party makes life harder for Alcorcón |newspaper=Marca |location=Madrid |last1=Jiménez |first1=Rubén |language=es |date=2 June 2013 |access-date=16 March 2016}}</ref> Delapan hari kemudian, kepindahan tersebut dibuat permanen selama empat tahun dan biaya sebesar R$18,738 juta.<ref>{{cite web |url=http://www.espnfc.com/spanish-primera-divisi%C3%A3%C6%92%C3%A2%C2%B3n/story/1473222/null |title=Madrid announce Casemiro deal |website=ESPN FC |date=10 June 2013|access-date=19 December 2013}}</ref><ref>{{cite news |url=http://www.gazetaesportiva.net/noticia/2013/06/sao-paulo/real-madrid-anuncia-oficialmente-a-compra-de-casemiro.html |title=Real Madrid anuncia oficialmente a compra de Casemiro|trans-title=Real Madrid officially announce purchase of Casemiro |newspaper=Gazeta Esportiva |language=pt |date=10 June 2013|access-date=10 June 2013|url-status=dead|archive-url=https://web.archive.org/web/20130613132900/http://www.gazetaesportiva.net/noticia/2013/06/sao-paulo/real-madrid-anuncia-oficialmente-a-compra-de-casemiro.html|archive-date=13 June 2013}}</ref><ref>{{cite web |url=http://www.saopaulofc.net/media/1394115/balanco2013b.pdf |title=Relatório da diretoria 2013|trans-title=Directorial report 2013 |publisher=São Paulo FC |language=pt |date=18 April 2014|access-date=9 June 2015}}</ref>
=== Porto ===
Casemiro dipinjamkan ke [[FC Porto|Porto]] pada 19 Juli 2014, dalam pinjaman selama satu musim. Dia mencapai 41 pertandingan secara keseluruhan untuk klub Portugal, mencetak empat gol, termasuk [[tendangan bebas]] pada 10 Maret 2015 dalam kemenangan kandang 4-0 atas [[FC Basel|Basel]] di babak 16 besar [[Liga Champions UEFA 2014–2015|Liga Champions UEFA]].
