Pimco head of marcoms Anne Fairchild Jones said the company had brought in Penrose last month, following a three-way pitch also involving WMC.
The brief, which is believed to be worth £100,000, is to raise Pimco's profile in the UK and Europe.
'We're keen to make pension funds aware of the full fixed-income toolkit,' Fairchild Jones told PRWeek.
Pimco managed more than £144bn in 2000, but now manages more than £275bn worldwide, £20bn of this in continental Europe.
In recent years, falling stock market returns and the increasing liability of pensioners' longer life-spans has made fixed-income funds more popular with the trustees of pension funds.
A revival in share prices could mean that pension funds that are over-reliant in bonds would lose out on more attractive yields.