Bootstrap 5 (update 2021)
In Bootstrap 5 (see this question), ml-auto has been replaced with ms-auto to represent start instead of left. Since the Navbar is still based on flexbox, auto margins OR flexbox utility classes are still used to align Navbar content.
For example, use me-auto...
<nav class="navbar navbar-expand-lg navbar-light bg-light">
<div class="container-fluid">
<a class="navbar-brand" href="#">Brand</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarContent">
<ul class="navbar-nav me-auto mb-2 mb-lg-0">
<li class="nav-item">
<a class="nav-link active" href="#">Home</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Link</a>
</li>
</ul>
<ul class="navbar-nav">
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-bs-toggle="dropdown" aria-expanded="false"> Menu </a>
<ul class="dropdown-menu dropdown-menu-end" aria-labelledby="navbarDropdown">
<li><a class="dropdown-item" href="#">Action</a></li>
<li><a class="dropdown-item" href="#">Another action</a></li>
</ul>
</li>
</ul>
</div>
</div>
</nav>
Bootstrap 5 right align Navbar content
Bootstrap 4 (original answer)
Bootstrap has many different ways to align navbar items. float-right won't work because the navbar is now flexbox.
You can use mr-auto for auto right margin on the 1st (left) navbar-nav.
Alternatively, ml-auto could be used on the 2nd (right) navbar-nav , or if you just have a single navbar-nav.
<nav class="navbar navbar-expand-md navbar-light bg-light">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="navbar-nav mr-auto">
<li class="nav-item active">
<a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Features</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
</ul>
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link" href="#">Login</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Register</a>
</li>
</ul>
</div>
</nav>
https://codeply.com/go/P0G393rzfm
There are also flexbox utils. For example use justify-content-end on the collapse menu:
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
<div class="container-fluid">
<a class="navbar-brand" href="#">Brand</a>
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse justify-content-end" id="navbarNav">
<ul class="navbar-nav">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Contact</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Pricing</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Download</a>
</li>
</ul>
</div>
</div>
</nav>
Or when you have 2 navbar-navs, use justify-content-between in navbar-collapse would work to even the space between the navbar-navs:
<div class="navbar-collapse collapse justify-content-between">
<ul class="navbar-nav mr-auto">
..
</ul>
<ul class="navbar-nav">
..
</ul>
</div>
Update for Bootstrap 4.0 and newer
As of Bootstrap 4 beta, ml-auto will still work to push items to the right. Just be aware the the navbar-toggleable- classes have changed to navbar-expand-*
Updated navbar right for Bootstrap 4
Another frequent Bootstrap 4 Navbar right alignment scenario includes a button on the right that remains outside the mobile collapse nav so that it is always shown at all widths.
Right align button that is always visible
Related: Bootstrap NavBar with left, center or right aligned items
