The contest was delicately poised with five minutes remaining but the hosts finished in style, Keane’s well-taken goal putting a flattering gloss on the final scoreline.
Despite conceding the opening score courtesy of a Jamie Wall free in the first minute, UCD delivered a major body blow to Mary Immaculate’s ambitions when Walter Walsh fired home after a surging run a minute later.
The visitors recovered with Wall firing two sumptuous scores in quick succession to restore parity before John Power fired over at the opposite end following Walsh’s precise pass.
Keane and Walsh edged UCD clear by the end of the first quarter but with Colm Galvin gaining in influence, Mary Immaculate remained in the hunt thanks to a brace of Wall frees.
Finally, the hosts began to showcase their attacking threat with David Treacy and Jack Guiney restoring their advantage as the snow showers fell.
That last year’s finalists remained just three points in arrears at the interval was down to Wall, with the Kilbrittain clubman firing a 20-metre free beyond Billy Leydon four minutes before the break.
On the resumption, UCD fired a plethora of wides, and the visitors’ ambitions were kept alive thanks to scores by Lar Considine and Galvin.
However, their efforts proved in vain against a UCD defence for whom Willie Phelan and Matt O’Hanlon excelled and the hosts pulled clear at the death thanks to a brace of long-distance points by Guiney and Keane’s unerring finish past Niall Kelly in the 59th minute.
UCD now travel to Cork to take on holders UCC in the quarter-finals next week.
Scorers for UCD: J Guiney 0-8 (0-4f, 0-2 ‘65’), W Walsh, C Keane 1-2, J Power, D Treacy, C Buckley, C O’Shea 0-1 each.
Scorers for Mary Immaculate: J Wall 1-5 (1-3f), C Galvin 0-2, L Considine 0-1.
UCD: B Leydon (Kilkenny); B O’Carroll (Dublin), W Phelan (Kiljenny), J Gannon (Kilkenny); B Coughlan (Waterford), M O’Hanlon (Wexford), W Egan (Cork); J Lyng (Kilkenny), C Buckley (Kilkenny); W Walsh (Kilkenny), D Treacy (Dublin), P Murphy (Tipperary); J Power (Kilkenny), J Guiney (Wexford), C Keane (Galway).
Subs: C O’Shea (Galway) for Lyng and J McDowell (Kilkenny) for Power (59).
MARY IMMACULATE COLLEGE: N Kelly (Westmeath); N Wynne (Offaly), C Barry (Tipperary), A Ryan (Tipperary); L Corry (Tipperary), S Kennedy (Tipperary), E Hogan (Tipperary); C Galvin (Clare), T McGrath (Tipperary), J Hannon (Limerick), D Reidy (Limerick), L Considine (Limerick); J Wall (Cork), B McCarthy (Waterford), D Ferncombe (Tipperary).
Subs: N Cleary (Offaly) for McGrath (46), PJ Keane (Kerry) for McCarthy (48), T Dowling (Laois) for Considine and E Hogan (Clare) for Ferncombe (54).
Referee: Brian Gavin (Offaly)