Alan Harris’s placards included Leah Haeger’s full name and caused her to feel “shame and embarrassment”, a court heard.
The stalker resorted to the extreme measure after pestering and following his ex in the wake of their split.
Harris, 58, has now been given a 12-month restraining order, banning him from contacting her.
Prosecutor Laura Jenking-Rees said Harris and Ms Haeger had been in a two-year relationship until July 2023.
After the break-up he started sending flowers and approaching the eyelash technician at her workplace in Southampton “with the hopes of trying to speak to her”.
Ms Jenking-Rees said: “She told him to leave as she was working. She did not want any contact from him.
“The behaviour persisted and on August 25 Mr Harris then decided to obtain six large signs – some saying ‘Leah Haegar I love you’ – and place them along her route to work.”
On another occasion he followed Ms Haeger in his car. The prosecutor added: “She made it very clear that all the behaviour from him was unwanted.
“The behaviour made her feel scared because she didn’t know what he would do next. She said since the incident her mental health has declined massively.”
In a victim impact statement to Portsmouth magistrates Ms Haeger said: “I feel shame and embarrassment, especially as [Harris] put my full name on the signs he made.”
She added: “I would like this behaviour to stop.” Saleem Chaudhry, in mitigation, told the court: “He is remorseful for his actions.
“It’s quite clear that his approach to the breakdown of the relationship had been somewhat immature.
“He never intended to cause the distress that he did.
“There is a degree of embarrassment as well to the way he’s acted.”
He added: “He thought he was trying to woo her back but clearly not.”
Harris, of Fareham, Hants, admitted one count of stalking without fear, alarm, or distress.
As well as a restraining order, Harris will also complete an 18-month community order with 100 hours of unpaid work, and 39 days of rehabilitation activities.