Consider the coordinate system as shown below and unit vectors along x and y, $\hat{i}$ and $\hat{j}$. The cross product of these unit vectors as given here is equal to $\hat{k}$. However, when I apply the right-hand rule, point my 4 fingers in the direction of $\hat{i}$ and curl them in the direction of $\hat{j}$ I get my thumb pointing towards $\hat{-k}$.
Where am I going wrong?

I think that you drew the orientation of the diagram wrong.