Xièxie nǐ de bāngmáng, nǐ jiǎnzhí shì wǒ de xiǎotiānshǐ.
Thanks for helping — you're really my little angel.
Tips
usage
Mostly for children and, affectionately, for anyone who saves the day with a kind act. On Chinese social media it's also a common term for young K-pop/C-pop idols and cute streamers.