Veteran France striker Giroud won the competition with Chelsea in 2021 and wants to continue his Indian summer at Milan with another triumph after winning the Serie A title last season.
Milan host local rivals Inter on Wednesday in the first leg of the biggest local derby the Italian city has seen for nearly two decades.
"I'm motivated more than ever. For me it's a big opportunity to win it again. Almost 37 years old but still hungry like a young boy," Giroud told reporters.
"In football it's never good to underestimate the others. I know what I'm talking about. At that level every single game is very tough and it's on small margins, small details, that you win it."
Giroud was a key figure in Milan's league title win this time last year and this season has netted five times in his team's impressive run to a blockbuster derby in the last four.
He scored the decisive goal which sent Milan through at the expense of Napoli, who last week dethroned the seven-time kings of Europe as champions of Italy.
'JUST WANT TO DREAM'
Milan are gunning for their first Champions League final since the last time they won the competition back in 2007.
"We are focused on Inter and we just want to dream," added Giroud.
"This club is special... Last year I couldn't hope for better than to win the Scudetto first year and in the second year still be in the race for the top four and in a semi-final of the Champions League. I'm very proud of this team."
