The Woodlands fighter took all three scorecards after a gruelling contest with the rated Foster in Birmingham.
Cunningham upset the applecart by outclassing Gamal Yafai to win the European title in May.
And he did so again on this occasion as he ripped more titles away from a home fighter.
The victory sealed his status as a three-weight Commonwealth champion having won the crown at both bantamweight and featherweight in the past.
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And it saw him claim the prestigious British title for the first time in a storied career.
The 32-year-old has long held a reputation as a game opponent with a tremendous toughness and no shortage of skill.
The tattoo across his chest, reading ‘the underdog who never lost hope’ looked set to define the career of a nearly man.
But it has taken on fresh and more poignant meaning this year as he has enjoyed an incredible renaissance to reach new heights.
His clash with Foster was a close one throughout but he claimed cards of 114-113, 115-114 and 116-112.