Travel From Venice to Ljubljana

Definitely Flix Bus. They are reliable, safe and prompt.

Option #3: GoOpti Shuttle. I've never used this shuttle, but it is highly recommended on this forum.

https://www.goopti.com/en/

My husband and I took a GoOpti last summer from Ljubljana to Venice...I assume it would likely be the same experience either direction. It was a really reliable service and I recommend it for sure. We were in a shared van with several other couples...van was nice and clean and driver was safe. Also, picked up and dropped off on time.

GoOpti looks like a great choice for this route because it’s about $50-$55 for 2 travelers in a shared vehicle rather than $50 for 2 on a big bus.

I used GoOpti from Ljubljana to Trieste and then took the train to Venice. I was pleased with GoOpti's service.

Edited to add: I spent a few nights in Trieste, thus the change of transport.

Thanks very much for everybody's recommendations!