The mouth of the busy waterway was shut as several vessels joined the RNLI in a swift rescue operation.
The crew of the training yacht from the Gosport-based Clipper round the world race organisation had been powerless to control her when the engine cut out in difficult weather conditions yesterday morning.
Buffeted by high winds and a strong tide, the 60ft vessel was pushed across the harbour entrance from the Gosport side towards Old Portsmouth before running aground on the shoreline near the Victoria Pier at the Hot Walls.
An RNLI spokesman said: ' RNLI Portsmouth Lifeboat was requested to launch to reports of a 60ft Clipper Yacht that had run aground at Portsmouth harbour entrance.
'With people on-board and rough conditions the Atlantic 85 Lifeboat, Norma T, launched quickly and raced to the scene within 12 minutes.
'On arrival the lifeboat was met by MOD Police launch Sir Geoffrey Rackham and two larger commercial vessels which had already established a towline and was starting to ease the yacht free.
'Blocking the busy harbour and reversing into the conditions, Windfarm supply vessel, The Sure Pilgrim, was able to slowly drag the training yacht backwards away from the pier and into clear water until further assistance could be given.
'Portsmouth Lifeboat and the MOD Police Launch inspected the casualty yacht for signs of damage while commercial Tug Gaurdsman secured a bow line to better control yacht until Bembridge RNLI arrived on scene to take over and recover the vessel to Gosport marina.'