The link Image Analyst gave has all the online trainings that are available. Currently Onramp is the only one that's free*.
When you say "with certification", do you mean that you can get something that says you completed it? In which case, they all have a progress report you can download and share.
If you mean the formal MATLAB Certification program, you can take the courses online or in-person that will cover the skills and competencies that are tested in the certification exam, but the exam is still a separate event that you have to register for. The training courses are not direct exam prep; instead, they are the most efficient way to learn the general content that is covered by the exams. MATLAB Fundamentals covers the skills tested in the Associates level exam. Three different further courses cover the Professional level exam.
[*] Unless you're at a school with the right license agreement, in which case they're all freely available to you!
