Aishwarya Rai Bachchan attended a reception at 10 Downing Street with Samantha Cameron on behalf of the charity Smile Train, this week.
Smile Train is an international children's charity which aims to provide treatment to children with cleft lips and palates.
Celebrating the achievements of the charity, the event marked the one millionth smile surgery.
Speaking at the event, Smile Train Goodwill Ambassador Rai Bachchan said: "There are so many of us who lead such blessed lives. I truly believe it's time to share our blessings. Working with Smile Train, if I can make a difference in families' lives, it will certainly make me feel honoured and blessed.
"There are a lot of children with clefts around the world who so desperately need help, but can't receive timely care because their families cannot afford this surgery or are ill-educated about this condition. It's time we smiled together in our lifetime - healthy and happy!"
Smile Train's CEO Susannah Schaefer commented: "The work Smile Train does is dependent on donations through corporate partners, fundraisers, independent donors and sponsors, and we are privileged to have some of the people who have supported Smile Train over the years with us today.
"Although we have helped more than one million children, there are still millions more with unrepaired clefts in the developing world who need our help. It is Smile Train's mission to provide each one of these children with free cleft repair surgery and related treatment so every child can experience the true power of a smile."
Aishwarya Rai Bachchan has also featured in a video for Smile Train, in which she imagines how different her life might have been if she had a cleft lip.
For the last 15 years, Smile Train has focused on providing the millions of children around the world born with clefts the same opportunities as a child born without a cleft, by providing 100% free cleft lip and palate repair surgeries.