Alaba who will don Ramos' number four shirt believes he's joined the side to be himself and not as replacement for the Spaniard.
"We all know Ramos was here for a long time and wore this number, becoming the leader of this team," Alaba said.
"But the truth is that yesterday I spoke to the club and they told me that right now it's the only available squad number. I didn't want to start asking other players if they wanted to swap.
"I'm honoured to wear the number four, it's a source of great pride and motivation for me and I want to do it justice.
"But I'm not here to compare myself to other players or replace them, I'm here to be David Alaba."
Alaba joined Real Madrid, signing a five-year deal on a free transfer from German champions Bayern Munich in May and will reunite with his former boss Carlo Ancelotti.
The 29-year-old was very successful at Bavaria and he is considered as one of the best players of this generation.
The two-time Champions League winner started his professional career as a left-back, but was deployed at the heart of defence during his latter days at the Allianz Arena.
Alaba played over 400 games for Bayern Munich in all competitions between 2010 and 2021. He scored 33 goals and provided 55 assists in the process for the Bavarian giants.
He is expected to play a major role in Ancelotti’s team, who will be seeking to reclaim La Liga, Copa del Rey and Champions League title.
Sergio Ramos, 35, won five La Liga titles with Los Blancos, four UEFA Champions League trophies, four FIFA Club World Cups, two Copa del Reys among numerous other honours before his 16-year stint at Santiago Bernabeu expired in June.
