Williams teamed up with Jabeur on Wednesday (AEST) to record a thrilling win over Marie Bouzkova and Sara Sorribes Tormo in her first competitive outing since last June, when she was forced to retire from her first-round Wimbledon clash with Aliaksandra Sasnovich through injury.
Having been granted a wildcard entry to the year's third grand slam, which begins next week, Williams is bidding for her first major title since winning 2017's Australian Open.
But speaking after her successful return to the court, Williams admitted her comeback had been far from certain.
"Did I ever doubt I would return? Absolutely, for sure. I would be dishonest if I said it wasn't and now my body feels great," she said.
"I definitely felt good out there and I was talking with Ons in the first set saying 'we're not playing bad' because they were just playing really good in that first set.
"But obviously winning, getting more balls and playing a little bit more made us feel a lot better. It definitely felt reassuring. It has been clicking in practice and now it seems like it is clicking. It is doubles but it still means a lot to both of us to be in it."
Williams and Jabeur will face Shuko Aoyama and Chan Hao-Ching in Eastbourne's doubles quarter-finals after posting an impressive 2-6 6-3 13-11 victory in their first outing.
With Williams now ranked 1,204th in the world and aged 40, speculation has abounded as to whether her SW19 appearance will mark the beginning of a farewell tour for the seven-time Wimbledon champion.
However, Williams is not rushing to make any further decisions about her future in the game.
"You know what, I am literally taking it one day at a time. I really took my time with my hamstring injury so I am not making a ton of decisions after this," she added.
"I did a lot of non-training in the beginning obviously and after I couldn't play New York [2021's US Open] I went cold turkey of not working out.
"It felt good, but I always try to stay semi-fit because you never know when you are going to play Wimbledon.
"I love tennis and I love playing otherwise I wouldn't be here, but I also love what I do off the court."