The conservation watchdog has announced that it is backing the plans - by lesser-known Belgian practice Robbrecht en Daem - to extend the institution into the Grade II-listed Whitechapel Library.
It is illustrating its support with a small grant of £35,000 towards the proposals, which are budgeted to cost £10 million.
EH is particularly pleased with the plans as the library has long resided on the Buildings at Risk register.
Nick Collins, EH's east London boss, said: 'EH is an enthusiastic supporter of this scheme and has given the Whitechapel Gallery advice on creating imaginative linkages between the two buildings and on the general approach to the restoration of the Library.
'We are delighted to be able to contribute financially to the project by giving a grant for the repair of this landmark building's distinctive exterior, which features a very fine frieze of putti(winged cherubs).'
Robbrecht en Daem's planned expansion ( pictured) will see galleries moved into the neighbouring library building - which will itself move to a new home in Mile End.
There are also proposals to build a street-level restaurant, expand the bookshop and provide public access to the gallery's archive for the first time in its 100-year history.