The British number four finished the job against Tamara Korpatsch on Court One, winning 6-7 (7) 7-5 6-2 in a match that was carried over from Monday night.
It was suspended at 10.40pm due to the local curfew tied at one set all and Watson came back in style on Tuesday with an impressive third-set performance, breaking her German opponent twice.
The win allowed her to exorcise the Court One ghosts of last year where she squandered match points to lose to Kristie Ahn in the first round.
Watson was emotional after the match when asked what the win meant to her.
“These are the moments you dream of as a little girl,” she said in her on-court interview.
“I don’t know why I’m getting emotional. I think I have had a really rough couple of years, like so many other people have. So this means a lot.
“I had a bit of a disaster match last year on this court, having match points. I really wanted to turn it around and win this year.”