The children’s charity has released a statement saying that as a result of the tragic case of Smith, it will no longer advertise on the site because it "puts the welfare of children first".
Vodafone claimed it had stopped advertising on the site and is investigating whether any advertising has appeared on the site recently.
The telecoms giant was recently commended for its work protecting children online by David Cameron and has had its Digital Parenting Guide plugged on a Conservative-backed website called ‘protecting your children’.
A Vodafone spokeswoman said: "Of the two agencies that we use to place advertising online, one has not placed any of our adverts on the site since last year and the other has recently stopped using it.
"We expect our advertising partners to share our values and are investigating whether our advertising has appeared on Ask.fm recently."
A digital marketing expert has claimed there still remains a transparency issue when it comes to online advertising, with brands having a lack of visibility about where their ads appear.
Andrew Goode, chief operating officer at content verification firm Project Sunblock, said: "In an increasingly social media world, companies need more reassurance about where their collateral is appearing on the internet.
"We’ve already experienced a number of our clients actively remove their content from Ask.fm."
Smith is the fourth teenager in
Ask.fm has issued a statement lamenting Smith’s death as a tragedy and claiming it encourages parents and users to report bullying via an in-site report button or through the website’s contact page.