The 19-year-old has moved to Palmerston Park on loan for the remainder of the season and will now continue his development under Johnston at the Scottish Championship outfit.
Mebude made his debut for Gers senior team in the 2018/19 season, clocking up minutes coming off the bench against Kilmarnock in the Scottish Premiership, but has since struggled to return to the first team fold, although he has been a regular in the youth teams.
Johnston expressed his delight at landing Mebude’s signature and revealed that he has been trying to rope in the Rangers starlet in each of the last three transfer windows.
The Queen of the South boss feels Mebude’s style of play will complement the other attackers he already has at his disposal as he tipped the teenager to flourish at his new home.
“Dapo is a player I have admired for a long time”, Johnston told Queens’ official site.
“I have tried to bring him to the club the last three transfer windows so it goes without saying that I am delighted that we have managed to secure him this time.
“This gives him a chance to play regular football and kick on with his career.
“He is young so is enthusiastic and full of energy and I think he will complement the players we already have.
“Again, we must thank Rangers for allowing the loan to happen.”
Mebude is set to go into the senior squad that will face Greenock Morton at the weekend in the league and has been handed the number 29 at Palmerston Park.