The LA Galaxy footballer explained that the new arrival "amazes" him, reports The Daily Telegraph.
Speaking at the launch for his new fragrance DB Homme in Los Angeles, he revealed: "The boys never slept when they were babies. Harper is totally different.
"She sleeps from, like, 11 o'clock at night till 7.30 in the morning, which at 3 months old, is kind of amazing. So, we are very lucky."
Beckham continued: "She is very feminine in every way. I've never had that before. I've never seen that before.
"So, everything she does, it kind of amazes me. Every time she moves or she makes a noise, it's amazing having a little girl."
Beckham's wife Victoria gave birth to daughter Harper Seven in July.
> David Beckham: 'Harper Seven will work in fashion'
> David Beckham: 'Breastfeeding is incredible'
> Victoria Beckham: 'I can't leave Harper Seven alone for a minute'
Watch David Beckham discuss Harper Seven below: