How to keep a checkbox and label on the same line in a Rails form?

It looks like you're using Bootstrap, so I recommend adapting your view code to use the horizontal form layout described in this section of the Bootstrap docs: https://getbootstrap.com/docs/4.3/components/forms/#horizontal-form

The comment on the answer is correct, but it assumes some nuance of understanding about order of elements.

The correct answer is as follows:

<%= f.check_box :terms_of_service %>
<%= f.label :terms_of_service, "I agree to the #{link_to 'Terms of Service', policies_path}.".html_safe
                             , {class: "checkbox inline"} %>

Two things are necessary:

1. The class on the label element
2. The checkbox element has to be before the label element.

This is obvious once you see it working, but all the other samples for form_for always have the inputs after the labels and you need to change that up for checkbox.

 <br>
  <%= f.check_box :terms_of_service, :style => "float:left;" %>
  <%= f.label :terms_of_service, "I agree to the #{link_to 'Terms of Service', policies_path}.".html_safe, :style => "float:left;" %>
  <br>

According to the bootstrap wiki, it must be

<label class="checkbox">
  <input type="checkbox"> Check me out
</label>

which in Ruby on Rails is

<%= f.label :terms_of_service do %>
  <%= f.check_box :terms_of_service %>
  I agree to the <%= link_to 'Terms of Service', policies_path %>.
<% end %>