Fellow Kiwi Cameron Norrie also reached the doubles quarter-finals at the same event.
Partnering up with Australian Harry Bourchier the pair reached the quarter-finals before suffering a 4-6 3-6 loss to Christian Garin (CHI) and Jorge Panta Herrreros (PER).
The Kiwi juniors now focus on the lead in events on grass prior to Wimbledon playing in the Grade 2 ITF in Germany and the Grade 1 ITF in Roehampton before heading to Wimbledon Juniors.
Fanning is a direct entry into Wimbledon main draw with Norrie currently 10 places out of qualifying.
Meanwhile, New Zealand tennis No 1 Marina Erakovic has lost her opening round match early this morning (NZT) at the WTA Eastbourne Championships.
Erakovic lost 5-7 1-6 to Tamira Paszek of Austria.
The Kiwi is yet to play her first round doubles match.
Erakovic and partner Tamarine Tanasugarn (THA) face world number two pairing Liezel Huber and Lisa Raymond (USA) in the opening round.
It's a rematch of last year's Wimbledon quarter-final where Tanasurgarn and Erakovic upset the highly ranked duo 13-10 in the third set super-tiebreak.
The doubles match is scheduled for overnight, Wednesday morning NZ time.