Chris Nelson, from Eskbank, is understood to have been visiting a friend in the Dutch city.
But the 24-year-old, who had recently moved to Germany, disappeared four days ago after failing to return from an early-morning walk in the Nieuwmarkt area of the city centre.
Sister Rebecca said he had been homesick but was set to return to Scotland permanently next month.
The 22-year-old said: “They went to Amsterdam on Saturday to visit friends. They had a nice touristy day and then they sat and had dinner on Saturday evening – and then on Sunday morning he went for a walk and just didn’t come back. His phone is off – we have tried contacting him countless times.
“He has the gift of the gab and is just such a beautiful person. He smiles constantly and just makes everybody happy.
“I can’t describe how much my brother just walked into a room and lit it up. You would meet him for two seconds and fall in love with him.
“He was homesick, we all knew that. But it was nothing untoward.”
An appeal posted by a friend in Amsterdam said loved ones were now “very worried” for his wellbeing.
It read: “My friend Christopher Nelson is missing. He came together with his fiancée on Saturday to stay for the weekend.
“He left my house on Sunday morning at around 5.45am for a walk but he did not return to the house.
“It was his first time in Amsterdam and he is not familiar with the city at all. I am afraid he couldn’t find his way back to my house at Recht Boomssloot, as he did not have the address on him either.
“So he might have asked around for the way. The weather was stormy and rainy and he was only wearing a black hoodie. Friends and family are very worried that something has happened to him. He is unreachable, his phone is off.”
It is understood Mr Nelson’s parents, Scott and Donna Nelson, travelled to Amsterdam earlier this week to help in the search.
The former bar manager and NHS pharmaceutical technician – who previously worked at the Buffalo Grill in Stockbridge – had recently moved to Kaarst, just outside Dusseldorf, to live with his German fiancée and was working as a labourer there.
Mr Nelson – who is described as 5ft 9in tall, with green eyes and red hair – was working as a bar manager in Scotland when he met his partner, Stephanie. The couple decided to move to Germany several months ago.
Dutch police are appealing for information and have issued a missing persons notice, stating: “At the time of his disappearance he wore grey jeans, a white Nike shirt with a coloured front, a black vest with hood, black Nike sneakers and he wears glasses with dark frame. If you have any information on the whereabouts of this missing person, please contact the police at 0800-6070.
“From outside the Netherlands, please dial +31793459876.”