Create URL hyperlink in R Shiny?

You can use html tags whatever you want to tag

    tags$a(href="www.rstudio.com", "Click here!")
## <a href="www.rstudio.com">Click here!</a>

By using paste, you're treating the url as a string. The function you want to use here is tagList:

runApp(
  list(ui = fluidPage(
     uiOutput("tab")
    ),
  server = function(input, output, session){
    url <- a("Google Homepage", href="https://www.google.com/")
    output$tab <- renderUI({
      tagList("URL link:", url)
    })
  })
)