The world number 37 suffered a disappointing Australian Open campaign, bowing out to Gilles Simon in the second round, but will return to his native Croatia eyeing a fourth win in six years at the ATP 250 Series event.
Cilic, a winner in 2009, 2010 and 2013, clinched the title last year with a 6-3 6-1 victory over Jurgen Melzer and will begin his defence against compatriot Mate Delic - a 20-year-old wildcard.
The number five seed has the chance to overtake coach and former world number two Goran Ivanisevic in terms of ATP titles won in Croatia with victory in Zagreb, after Ivanisevic picked up four winner's medals in his homeland.
"Goran is an excellent coach. He passes everything he knows on to me. We have had super preparations and my inner feeling is that I play better than before. All I have to do now is demonstrate this in the matches," Cilic told the tournament's official website.
"(Ivanisevic's record) will not be an additional motive for me. Naturally, it would be nice to raise the winner's trophy again. But, our main goal in this season is to achieve the best possible results at Grand Slam tournaments and at ATP Masters Series."
World number 12 Tommy Haas will make his debut in Zagreb as top seed, having recovered from the shoulder injury that forced him to retire during his first-round clash with Guillermo Garcia-Lopez at the Australian Open.
Mikhail Youzhny and Ivan Dodig, both former winners of the competition, are seeded second and fourth respectively, although two of the world's top 20 have been ruled out due to injury.
Croatian Milos Raonic, number 11 in the world, misses out with an ankle complaint, while Grigor Dimitrov cited his need for rest and recovery as his reason for withdrawal, having suffered a recurring leg injury.
Dimitrov, who reached his first grand slam quarter-final in Melbourne, explained his decision, as he said: "I am very disappointed that I won't be able to compete at PBZ Zagreb Indoors this year.
"The accumulations of matches in Australia and a leg injury makes necessary to give my body a rest to recover."
|Pederson unwilling to comment on Wentz amid ACL fears|
|Kane: Bring on the best in Champions League|
|Neville: Lukaku needs to believe amid Man United struggles|
|Fitzgerald now third all time in receiving yards|
|Eagles QB Wentz suffers knee injury|
|Messi best player of all time – Rakitic|
|Gattuso: I´m even tense playing football with my son|
|Suarez admits Villarreal red swung it for Barcelona|
|Villarreal win ´crucial´ for Barcelona boss Valverde|
|O´Hair and Stricker claim QBE Shootout crown|
|Sublime O´Sullivan equals major record with sixth UK Championship win|
|Villarreal 0 Barcelona 2: Suarez, Messi restore five-point LaLiga lead|
|AC Milan 2 Bologna 1: Bonaventura brace breaks Gattuso´s duck|
|Leinster end Exeter home streak, La Rochelle shine again|
|Texans QB Savage suffers concussion; brief return sparks controversy|
|Guardiola: Man City are an honest team|
|Snow joke! Bills and Colts play in brutal blizzard|
|Mourinho: Herrera denied clear penalty in derby defeat|
|Mourinho admits title race ´probably´ over|
|Josh Gordon scores first touchdown in four years|
|Simeone defends Atleti´s style after battling win over Betis|
|Manchester City´s 14th win on the spin sets new top-flight record|
|Manchester United 1 Manchester City 2: Otamendi strikes massive blow in Premier League title race|
|Bath concerned by injury to Wales forward Faletau|
|Allardyce praises ´brave´ Pawson after penalty decision|
|Atletico Madrid set club-record unbeaten run in LaLiga|
|Ajax 3 PSV 0: Eredivisie title race gets new lease of life|
|Klopp involved in post-match spat with reporter|
|Rooney backs awarding of ´clear penalty´|
|Mathews heaps praise on Lakmal as Sri Lanka end losing streak|
|Real Betis 0 Atletico Madrid 1: Rojiblancos make history to assuage Champions League pain|
|Klopp rages at referee after late penalty denies Liverpool|
|Shubhankar made to wait by weather|
|Liverpool 1 Everton 1: Late Rooney penalty secures unlikely derby draw|
|Napoli 0 Fiorentina 0: Sarri´s men miss chance to usurp Inter|
|Shakib returns as Bangladesh captain to replace Mushfiqur|
|Martial and Rashford both start Manchester derby as Jesus edges out Aguero|
|Joshua-Parker ´close to being locked in´|
|Neuer in no doubt over World Cup fitness|
|Wenger labels Saints sinners over time-wasting|
|Super-sub Giroud celebrates being Arsenal´s saviour again|
|Moeen aware England players must improve behaviour|
|Duckett handed maximum fine & suspended from England Lions|
|Southampton 1 Arsenal 1: Super-sub Giroud rescues last-gasp point|
|Firmino and Coutinho on bench for Merseyside derby|
|There´s snow rugby for Saracens as Clermont clash called off|
|Stoger ready to grab ´incredible opportunity´ at Dortmund|
|Career best for Lakmal in Sri Lanka rout|
|Boult: No need for four-day Test matches|
|Courtois keen to resolve Chelsea future|
|Borussia Dortmund sack Bosz, bring in Stoger|
|Moeen makes some strides as Curran impresses|
|Melbourne City 1 Central Coast Mariners 0: McCormack eases Cahill blues|
|Rigondeaux victory not a big win for ´superhuman´ Lomachenko|
|Dortmund to hold news conference with Bosz on the brink|
|Guardiola: I would retire if possession football did not work|
|Black Caps take control in Hamilton|
|LeBron leads shorthanded Cavaliers past 76ers|
|Stokes out for duck as England all-rounder continues to struggle|
|Lomachenko beats Rigondeaux by TKO to retain title|
|There´s no comparison, Ronaldo is best – Marcelo|
|Beal, Wizards seething after ´tough s***´ loss to Clippers|
|Baker Mayfield wins Heisman Trophy|
|Bradley revels in ´dream´ MLS Cup success|
|Valverde unsure about Mascherano future|
|Allegri pleased with Juve display|
|Angels intend to use Ohtani as a two-way player|
|Mourinho highlights City´s tactical fouls to ramp up ref pressure|
|Spalletti makes his point as Inter show they belong in Serie A title race|
|Toronto FC 2 Seattle Sounders 0: Altidore and Vazquez seal MLS Cup and historic treble|