In March, the United Kingdom government suspended its adverts from YouTube, following concerns they were appearing next to inappropriate content.
The reports led several big brands including Mars and Adidas to pull advertising from the site.
YouTube's recent issues with videos depicting child abuse and other offensive content are prompting the site to hire additional help.
"We need an approach that does a better job determining which channels and videos should be eligible for advertising", she said.
"Now, we are applying the lessons we've learned from our work fighting violent extremism content over the previous year in order to tackle other problematic content", Wojcicki wrote. In addition, YouTube would also "apply stricter criteria, conduct more manual curation, while also significantly ramping up our team of ad reviewers".
Wojcicki said that while Youtube was a "force for creativity, learning and access to information" she had also "seen up-close that there can be another, more troubling, side of Youtube's openness".
In a blog post, Ms Wojcicki explained: "Human reviewers remain essential to both removing content and training machine learning systems because human judgment is critical to making contextualised decisions on content".
She said Youtube would be speaking with advertisers and creators "over the next few weeks" to hone its approach.
On Monday, Alphabet's YouTube said it planned to add more people to identify inappropriate content in 2018, as the company responded to criticism over extremist, violent and disturbing videos and comments.
Ms Wojcicki said that staff had reviewed almost two million videos for violent extremist content since June.
We are also taking aggressive action on comments, launching new comment moderation tools and in some cases shutting down comments altogether.
The company has announced that it intends to employee 10,000 new staff to moderate videos on YouTube in 2018. Wojcicki claimed that since starting to use machine learning to flag videos of this nature, it has reviewed content that would have taken 180,000 people working 40 hours a week in the same time-frame to assess.